Which of the following sentences is correct?
a. she is the person whom he had found sleeping in the library.
b. that author is the one who i saw at the bookstore today.
c. against who did you think you would compete in the contest?
d. the musical group whom won the top prize are from my hometown.

The correct answer is option(b).  44°

Step-by-step explanation:

From the figure we can see a right angled triangle with one angle is x° and two sides are given.

To find the value of x

From the given figure we get the adjacent side of angle is given

Therefore we can write,

Cos x = Adjacent side/Hypotenuse

 = 15/21

 = 0.7142

x = Cos ⁻¹ (0.7142)

 = 44°

Therefore the value of x = 44°

The correct answer is option(b).  44°