what function models the data shown on the graph?

f(x) = 2(x – 5)(x – 1)

f(x) = –2(x – 5)(x – 1)

f(x) = 2(x + 5)(x + 1)

f(x) = –2(x + 5)(x + 1)

It looks like the parabola are going down, so  the coefficient should be negative,
B or C,
then we see that the parabola has x -intercepts (1,0) and (5,0)
these roots should be written as multiples 
x=1, so x-1=0
and 
x=5, so x-5=0,
so (x-1)(x-5) and negative first coefficient -2 at the same time. 
We can see only in the 
B. f(x) = –2(x – 5)(x – 1)