The vertex of a parabola is at the point (3,1), and its focus is at (3,5). What function does the graph represent?
A. f(x)=(x - 3)² - 1
B. f(x)=(x + 3)² - 1
C. f(x)=(x - 3)² - 1
D. f(x) = (x - 3)² + 1