Which of the following are Rabi crops only?

The correct answer is D, rainy. Kharif crops are sown in June and July with the onset of the south-west monsoon and harvested in September and October, because they need both high temperature and heavy rainfall while growing. Paddy, maize, jowar, bajra, tur, moong, urad, cotton, groundnut, soyabean and jute are the standard kharif crops of India.

Option A is wrong because crops sown at the beginning of winter, in October and November, are rabi crops such as wheat, barley, gram, peas and mustard. Option B is wrong because the short summer season between rabi and kharif is the zaid season, used for watermelon, muskmelon, cucumber and fodder. Option C is wrong because spring is not recognised as a cropping season in the Indian classification at all, so no crop group is named after it.

The correct answer is A, wheat. Wheat is the leading rabi crop of India. It is sown in October and November, needs a cool season of about fifty to sixty centimetres of rainfall for growth and bright sunshine at the time of ripening, and is harvested in March and April. Uttar Pradesh, Punjab, Haryana and Madhya Pradesh are its main producing States.

Option B is wrong because groundnut is a kharif oilseed sown with the monsoon, mainly in Gujarat, Rajasthan and Tamil Nadu. Option C is wrong because paddy is the classic kharif crop, needing more than a hundred centimetres of rainfall and standing water in the field. Option D is wrong because maize is grown as a kharif crop across most of India, although it is also raised as a rabi crop in parts of Bihar, which is why the question asks for the general classification.

The correct answer is D, cotton. In the colour coding of India's agricultural revolutions the Silver Fibre Revolution stands for cotton, the fibre crop of the black soil regions of Gujarat, Maharashtra and Telangana. The plain Silver Revolution, without the word fibre, refers to eggs and poultry, and the two are deliberately offered together in papers.

Option A is wrong because leather and cocoa belong to the Brown Revolution. Option B is wrong because oilseeds, especially mustard and sunflower, belong to the Yellow Revolution. Option C is wrong because jute has no colour revolution of its own; it is simply called the golden fibre, which makes it a tempting but incorrect choice here. Learning the list, Green for food grains, White for milk, Blue for fish and Pink for prawn, settles this family of questions.

The correct answer is A, cotton. The pink bollworm is the most damaging pest of the cotton plant. Its larva bores into the boll and feeds on the developing seed and lint, so the damage is hidden until the boll opens, and it has developed resistance to some insect-resistant cotton varieties, which is why it keeps returning to the news.

Option B is wrong because silk is produced by the silkworm, which is reared rather than protected from pests of this kind, and the word bollworm itself points to a boll, a cotton structure. Option C is wrong because the main pests of mustard are the aphid and the sawfly. Option D is wrong because apple orchards suffer from the codling moth and the woolly aphid. Only cotton forms bolls, so only cotton can host a bollworm.

The correct answer is B, black soil. Black soil, also called regur or black cotton soil, covers much of the Deccan plateau and is formed from the weathering of lava. It holds moisture for long periods, develops deep cracks in the dry season that help aeration, and is rich in calcium carbonate, magnesium and potash, all of which suit a crop needing about 210 frost-free days.

Option A is wrong because laterite soil is leached and low in fertility, suited to cashew, tea and coffee after heavy manuring. Option C is wrong because red soil, formed from crystalline rock, is poor in nitrogen and humus and is used mainly for millets and pulses. Option D is wrong because peaty soil forms in waterlogged areas such as the Kerala backwaters and is used for rice, not cotton.