Which of these locations is a peninsular country?

The correct answer is C. Indonesia.

A peninsular country is one that is located on a peninsula, which is a landform surrounded by water on three sides. Indonesia is an archipelago, but it includes many land masses that are peninsular in nature, particularly in the regions of Sumatra and Java, where significant portions of the country are bordered by water. If you have more questions or need further details, feel free to ask!