owing statements is not true about the correlation (r) between the weight in pounds and gas mileage in miles-per-gallon for a sample of pickup trucks?...

Which of the following statements is not true about the correlation (r) between the weight in pounds and gas mileage in miles-per-gallon for a sample of pickup trucks? 

A. r must take a value between -1 and 1.

B.r is measured in pounds per gallon.

C.If heavier pickup trucks tend to also get lower gas mileage, then r < 0. 

D.r would not change if we measured these trucks in kilograms instead of pounds