Answer: B
We call the shared edge of two rectangles as H
In left rectangle we degrees of angles are 90, 45, 45
sin45 = H / x
√2/2 = H / x
H = √2/2 * x

In right rectangle we degrees of angles are 90, 30, 60
Sin30 = H / y
1/2 = H / y
H = 1/2 * y

So we have H = √2/2 * x and H = 1/2 * y
H = √2/2 * x = 1/2 * y
We multiply both sides to 2, then we will have :
√2 * x = y
Now we see that y is bigger than x because y/x = √2 (√2 which divides y to x, is more than 1, so y is bigger than x)
B is bigger