The volcanic Gaua Island is part of which Pacific country?

Option C

Vanuatu is a Pacific island country located in the South Pacific Ocean. The archipelago, which is of volcanic origin, is 1,750 kilometres (1,090 mi) east of northern Australia, 540 kilometres (340 mi) northeast of New Caledonia, east of New Guinea, southeast of the Solomon Islands, and west of Fiji. Gaua  is the largest and second most populous of the Banks Islands in Torba Province of northern Vanuatu. It covers 342 km².