When positive integer \(m\) is divided by positive integer \(x,\) the reminder is \(7\) and when positive integer \(n\) is divided by positive integer \(y,\) the reminder is \(11.\) Which of the following is a possible value for \(x + y?\)

I. 18
II. 19
III. 20

A. I only
B. II only
C. III only
D. II and III only
E. None

Answer: C

Source: GMAT Club Tests