Referring to the exhibit, an IPSec tunnel is established between SRXA and SRXB. A GRE tunnel is established between router A and router B. Users in LANA can ping users in LANB however large FTP transfers are failing.

What is causing the problem?

A.
The anti-replay service window size needs to be increased to 64.

B.
SRXB is running in transport mode.

C.
Fragmentation is not allowed on the IPSec tunnel.

D.
GRE over IPSec is not supported.