Problem Solving

\(M\) is a positive two-digit number. When the digits are reversed, the number is \(N.\) If \(K = M + N,\) which of the following is true?

A. \(K\) must be even.
B. \(K\) cannot be square.
C. \(K\) cannot be divisible by \(13.\)
D. \(K\) must be divisible by \(11.\)
E. If \(M\) is even then \(K\) must be even.

Answer: D

Source: Magoosh