A receiver channel was defined with MCAUSER set to blank and PUTAUT set to CTX.
Which of the following statements is true?

A.
The MCA will put messages with full administrative authority.

B.
The MCAUSER value is dynamically set with the user ID extracted from the message header.

C.
The messages cannot be sent through the sender/receiver channels since the MCAUSER value is blank.

D.
The user ID is extracted from the message header and this user ID is used by MQ to make authorization decisions.