Given that $f(x) = x^2 - 19$ and $g(x) = 4x + 20$, find $(g - f)(1)$, if it exists.\
Select the correct choice below and, if necessary, fill in the answer box to complete your choice.\
A. $(g - f)(1) = $ (Simplify your answer.)\
B. $(g - f)(1)$ does not exist.