Which of the following statements regarding insolation is/are correct? 1. Insolation is predominantly short-wave radiation, with wavelengths in the range of 0.39 micrometre to 0.76 micrometre. 2. Insolation is evenly distributed across the Earth because of the Earth's curved surface. Select the correct answer using the code given below.

The correct answer is A, 1 only. Insolation, the incoming solar radiation, arrives mainly as short waves centred on visible light, but the Earth's curved surface spreads it unevenly, so statement 2 is false. The Sun's surface is about 6,000 °C, so it gives out most of its energy at short wavelengths, chiefly in the visible band of about 0.39 to 0.76 micrometre. The Earth, being much cooler, sends energy back to space as long-wave infrared radiation, which greenhouse gases trap. Because the Earth is a sphere, the Sun's rays strike the equator almost vertically and the poles at a low slant. Slanting rays spread over a larger area and pass through more atmosphere, so the tropics get far more insolation than the poles; the tilt of the axis adds seasonal changes. Option B is wrong because statement 2 is false and statement 1 is true. Option C is wrong because the curved surface causes uneven, not even, distribution. Option D is wrong because statement 1 is correct. Exam tip: the Sun sends short waves, the Earth returns long waves; insolation is highest near the equator and least at the poles.