The graph shows the girth, in cm, of the trunk of an oak tree after different numbers of years: Line joining ordered pairs 0, 7 and 1, 8.5 and 2, 10 and 3, 11.5 and 4,13 and 5,14.5 What does the y-intercept of the graph represent? (1 point) The girth increases by 7 centimeters each year. The girth increases by 1.5 cm each year. The original girth was 1.5 cm. The original girth was 7 centimeters.