Answer: (D) 
Explanation:

Just a note on writing down these expressions: I recommend using parentheses whenever you can to avoid misinterpretation. An expression 1/x-1/y / 1/x+1/y could be interpreted by someone as 1/x-(1/y / 1/x)+1/y, which is a different thing.
Do you have a picture or sum?
He cannot make a rectangle with those measurements because the base of the rectangle need to be a least more that 1cm bigger than the height other wise its just a square