If I understand correctly, these are your options.
A. 3√√2
B. 3
C. 6
D. 6√2
E. 2√2
It appears that x is a side, but there must have been a picture with this problem. If the triangle belonged to a Pythagorean Triple, then 3√2 may be a good option. However, if this was a trig problem, then 2√2 is a likely option. If you post the picture it would help immensely.