Question from my statistics midterm I got wrong

[KingGordy]

This is the only question on my midterm I got wrong, but I've reviewed it closely and don't understand why. Hopefully someone smarter than me can explain it.

18) A study gathers data on the outside temperature during the winter, in degrees Fahrenheit, and the amount of natural gas a household consumes, in cubic feet per day. Call the temperature x and gas consumption y. The house is heated with gas so x helps explain y. The least-squares regression line for predicting y from x is y=1344-19x

The correlation between temperature x and gas usage y is r=-0.7. Which of the follwing would not change r?

A)Measuring temperature in degrees Celsius instead of degrees Fahrenheit.

B) Removing two outliers from the data used to calculate r.

C)Measuring gas usage in hundreds of cubic feet, so that all values of y are divided by 100.

D) Both A and C.

Any help would be appreciated.