A) g(x)= (x-5)(x-9)
This is the answer because basically you need to find the roots of the function, since the function g intersects the x-axis at x=5 and x=9 you can conclude easily that those are the roots.
If:
x=5
g(5)=(5-5)(5-9)=0(-4)=0
and
If:
x=9
g(9)=(9-5)(9-9)=(4)(0)=0
