She is slender in figure.

strong
well-built
stout
slim

The correct answer is D. slim.

Slender means having a relatively small amount of fat on the body, and being of a height and build that is not particularly heavy or bulky.

Strong means having a lot of physical strength.

Well-built means having a strong and healthy body.

Stout means having a large amount of body fat, and being of a height and build that is relatively heavy and bulky.