Do you know what "sine" means?
It is the opposite over hypotenuse.
You can think of it like:
Sine Opposite Hypotenuse Cosine Adjacent Hypotenuse Tangent Opposite Hypotenuse
Which comes out to be:
soh cah toa
Know that, we now know that the hypotenuse of the triangle is 41, and the shorter leg of the triangle is 9.
Using Pythagorean triples, we see that the is a 41, 40, 9 triangle.
this means that the tangent is 9/40, or D