the president can pocket veto a bill only if

a. it was produced by a conference committee
b. congress's session is ending
c. congress does not send it to him
d. it is a tax bill

b or d. i think b.

B is correct.

http://en.wikipedia.org/wiki/Pocket_veto

To determine the correct answer, let's break down the options and understand the concept of a pocket veto:

a. It was produced by a conference committee: The origin of the bill from a conference committee is not a requirement for a pocket veto.

b. Congress's session is ending: This is one of the conditions for a pocket veto. The President can use a pocket veto when Congress is adjourned or in recess and cannot override the veto due to the session ending.

c. Congress does not send it to him: If Congress does not send the bill to the President, it cannot be vetoed since there is no bill to veto.

d. It is a tax bill: A pocket veto applies to all bills (including tax bills), not just specific types of legislation.

Therefore, the correct answer is b. The President can pocket veto a bill only if Congress's session is ending, and they cannot override the veto due to the session concluding.