Hey there!
The sine is always equal to the opposite side divided by the hypotenuse. However, we do not have the hypotenuse length. So, we will use the Pythagorean Theorem to find it with the sides we do have.
8²+11²=185
√185≈13.6
Now, we will divide our opposite side, which is AC (8 cm) by our hypotenuse of 13.6
8/13.6≈ 0.588
Therefore, the answer is A) 0.588.
I hope that this helps!