Which of the following countries is in south asia?

Thailand.

When you think of southeastern Asia, think of the area between Asia and Australia. That's where Indonesia, Vietnam, Thailand, Singapore, Malaysia, the Philippines, Cambodia, Laos, Myanmar, Brunei and Timor-Leste lie.

All these countries have a primarily tropical climate year round, due to the fact that they are further south and are surrounded by water. The only countries that see winter-type weather are those on the mainland; Northern Vietnam and the Myanmar Himalayas.