Simplify the following expression, reduced to lowest term:
((1)/(x-3)+(1)/(x-4))/((1)/(x+3)-(1)/(x-4)):
a) (2x - 1)/(x² - x - 12)
b) (2x + 1)/(x² + x - 12)
c) (2x - 1)/(x² - x + 12)
d) (2x + 1)/(x² + x + 12)