Why are port numbers included in the TCP header of a segment?

PYQ RPSC Programmer 2011

1. A.

   To indicate the correct router interface that should be used to forward a segment

2. B.

   To identify which switch ports should receive or forward the segment

3. C.

   To determine which Layer 3 protocol should be used to encapsulate the data

4. D.

   To enable a receiving host to forward the data to the appropriate application

Attempted by 7 students.