Answer:
Answer A (or C. Both were very close)
Explanation:
I don't know what "please only answer if you know not to ask a question" means.
Since ∠ADB is 90° and ∠BAD is 36°, then ∠ABD is 180-90-36 or 54°.
You could just try using the Pythagorean Theorem for all the answer choices.
(a²+b²=c² where a and b are the legs and c is the hypotenuse)
A.
11²+8²=c²
121+64=c²
c=
c ≈ 13.60
B.
I don't need to prove this because the shorter legs' sum is greater than the hypotenuse and will not make a triangle.
C.
15.1²+11²=c²
288.01+121=c²
c=
c ≈ 18.68 ≈ 18.7
D.
I don't need to prove this because the shorter legs' sum is greater than the hypotenuse and will not make a triangle.
I think answer A is the best since it rounds closer to the answer in the row. It was pretty close between C and A so you can decide if you'd like but I suggest A because it's a closer rounding.