When designing a network that uses IPsec, which technique is suggested to avoid network fragmentation?

When designing a network that uses IPsec, which technique is suggested to avoid network fragmentation?
A . Reduce the MTU only in the WAN
B . Reduce the MTU on the side closest to the client
C . Reduce the MTU on the side closest to the server
D . Reduce the MTU on both ends of the TCP connection

Answer: D