For a positive integer n and nonzero digits a, b, and c, let A_{n} be the n-digit integer each of whose digits is equal to a; let B_{n} be the n-digit integer each of whose digits is equal to b; and let C_{n} be the 2 n-digit (not n-digit) integer each of whose digits is equal to c. What is the greatest possible value of a+b+c for which there are at least two values of n such that C_{n}-B_{n}=A_{n}^{2} ?

**Answer Choices**

A. 12

B. 14

C. 16

D. 18

E. 20