Correct Answer: Modest

Solution : The correct choice is the Fourth option .

Vain refers to excessive pride or admiration of one's own appearance or achievements. The most suitable antonym is Modest, which means having or showing a moderate or humble estimate of one's merits, importance, etc.,

The meanings the other options are as follows:

• An extrovert is an outgoing and sociable person who enjoys being with others.
• Selfish means concerned chiefly with one's own personal profit or pleasure at the expense of others.
• Stubborn means having or showing determination not to change one's attitude or position on something.

Therefore, the right answer is Modest.