I did this one yesterday, and my little brother had to tell me how to do it.
He says the answer is 2, which does not appear in any of the answer choices therefore the answer is E (empty).
First arrange the equation to csc^2theta = (1/4)
Now remember that csc is equal to (1/sin) so change it to sin.
Then flip both sides to get sin^2theta = 4
Now, square root both sides to get sin(theta) = 2
Therefore you see the answer is 2.
I was sitting at the comp for like 3 minutes when I asked him how to do this problem. He solved it in his head in about 3 seconds and then called me a ******.