simplify x+7/x^2+4x-21
a- 1/x-3; where x does not equal 3, -7
b- x-3; where x does not equal 3
c- 1/x-7; where x does not equal 7
d- x-7
a- 1/x-3; where x does not equal 3, -7
b- x-3; where x does not equal 3
c- 1/x-7; where x does not equal 7
d- x-7