Hi
from this picture and the colors used i' d say:
Vlan 10 has a gateway at Router 1 and Router 1 has no l3 interface for Vlan 20
Vlan 20 has a gateway at Router 2 and has no l3 interface for Vlan 10
So traffic will have to go from SW1 to R1 to leave the vlan 10 subnet and has to be routed to R2 which has an l3 interface for vlan 20
B is your answer i think.