The y-intercept of a parabola is 1, and its vertex is at (1,0). What function does the graph represent?

A.
f(x) = (x − 1)2
B.
f(x) = (x + 1)2
C.
f(x) = -1(x − 1)2
D.
f(x) = -1(x + 1)2