what is the correct RPF path toward the multicast source from R6?

Refer to the Exhibit.

Referring to the exhibit, what is the correct RPF path toward the multicast source from R6?

A.
R6-R5

B.
R6-R7-R4-R5

C.
R6-R4-R5

D.
R6-R4-R3-R2-R5