Well...
A.
8(2r) & 10r
This is incorrect because the second option would be if you added 8r to 2r, not multiplied 8 to 2r.
B.
6r + 3 & 9r
This is incorrect because you cannot add the 3 to 6r, because they are different.
C.
9(3r-4) & 27r - 36
This is correct because the two options are equivalent.
D.
r+r+r+r+r & r^5
This is incorrect because the first part would need to be r x r x r x r x r for it to be true.
yw.