Mala was often teased as corpulent by her friends.

The correct answer is

Corpulent means fat or obese. It is a negative word that is often used to tease or insult someone who is overweight.

The other options are:

• Belligerent: aggressive or warlike.
• Garrulous: talkative or wordy.
• Gaunt: thin and bony.

None of these words are as closely related to the meaning of the question as corpulent is.