The graph shows the girth of the trunk of a fir tree after different numbers of years:

Line joining ordered pairs 0, 5 and 1,12 and 2, 19 and 3, 26 and 4, 33 and 5, 40

What does the y-intercept of the graph represent?

A)The girth increases by 7 centimeters each year.
B) The girth increases by 5 centimeters each year.
C) The original girth was 5 centimeters.
D) The original girth was 7 centimeters.