to move the function c units up, add c to the whole funcion
you adde -9 so you moved up -9 units or down
see each choice
A. xint is where y=0, the xint for this equaion is 9, false
B. false, slopes were not affected
C. false, they clearly changed
D. yint is where x=0, the yint is -9, true
answer is D