The correct answer is: a) Shillong.
The only operational airport in Meghalaya is the Umroi Airport, located in Umroi, about 30 kilometers from Shillong. The airport was originally built by the British in 1942 as an airstrip for military purposes. It was later converted into a civilian airport in 1962. The airport has a single runway that is 2,200 meters long and 45 meters wide. It can handle aircraft up to the size of a Boeing 737. The airport is served by Air India and Alliance Air, which offer flights to Kolkata and Guwahati.
The other options are incorrect because they are not the locations of any operational airports in Meghalaya. Tura is a town in the West Garo Hills district of Meghalaya. Jowai is a town in the West Jaintia Hills district of Meghalaya. Nongstoin is a town in the West Khasi Hills district of Meghalaya.