If m and n are direct natural numbers, then which of the following is/are integer/integers?(1) m/n + n/m(2) mn × (m/n + n/m) × (m2 + n2)-1(3) mn/ (m2 + n2)Select the correct answer using the code given below.

• A. 1 and 2
• B. 2 only
• C. 2 and 3
• D. 3 only