Which Greek pilot is credited with using the south west monsoon winds to sail directly across the Arabian Sea to India?

The correct answer is B, Hippalus. Around the middle of the first century of the Christian era this pilot is said to have worked out the rhythm of the south west monsoon, after which ships ran straight from the mouth of the Red Sea to the Malabar coast instead of hugging the shore, cutting the voyage to roughly forty days and setting off the boom in Indo-Roman trade; the wind itself was named after him in Greek accounts. Option A is wrong because Megasthenes was the Seleucid ambassador at the court of Chandragupta Maurya and wrote the Indica. Option C is wrong because Ptolemy, of the second century, was the geographer who mapped the ports rather than a sailor. Option D is wrong because Nearchus commanded the fleet of Alexander down the Indus and along the Makran coast, three centuries earlier. The name Hippalus goes with monsoon and with the Periplus.