To verify that your PPTP implementation is working as you intended, you sniff the network after the implementation has been completed. You are looking for specific values in the captures that will indicate to you the type of packets received. You analyze the packets, including headers and payload. PPTP works at which layer of the OSI model?

A.
Layer 1

B.
Layer 2

C.
Layer 3

D.
Layer 4

E.
Layer 5