Simplify the following expression.

The correct answer is A. 37x + 87y.

To simplify the expression, you can distribute the negative sign to each term within the parentheses:
(63x + 73y) - (-26x + 14y) = 63x + 73y + 26x - 14y

Next, you can combine like terms by adding or subtracting coefficients of the same variable:
63x + 26x + 73y - 14y = (63x + 26x) + (73y - 14y) = 89x + 59y

Therefore, the simplified expression is 89x + 59y.