When a SIP message does not contain the "Allow" header, what is the sender telling the receiver about supported SIP methods? 

Answer options:

A. The sender supports all standard based SIP methods.
B. The sender does not support any SIP methods.
C. It is a malformed SIP message.
D. It is coming from an intermediate SIP entity.
E. The sender is not providing any information on what methods it supports.

E