Anyhow its B based on width of the space.
A is incorrect based on the front view.
Note the "arms" the left arm is longer. But in the front view it is shown that the space to the right is larger.
C is incorrect that from the front view, the arm lengths match up with the view provided. But when you look from the end view, its too short on the left side.
choice D is a mix of A and C errors.
check out the picture I uploaded versus yours. since it might be too small.