Actually, President John F. Kennedy no doubt received advice from most of the people listed above (except perhaps Earl Warren). The best choices would be answers A and D. His brother, Robert, was a confidant while serving as Attorney General. Theodore Sorenson was a special counsel who drafted many of Kennedy's letters during the Cuban Missile Crisis. Dean Rusk served as Kennedy's Secretary of State, while Bob McNamara was the Secretary of Defense. The President probably received advice from his Vice President, Lyndon Johnson, and probably even personal advice from his wife, Jackie.

The answer to this is going to depend on what your textbook or your teacher says.  There are two answers that could possibly be correct.

B and C are clearly not right.  Earl Warren was the Chief Justice of the Supreme Court.  That is not a political post and he was not an advisor of Kennedy's.  Johnson was Kennedy's vice president, but the two men were not close.  Johnson had been chosen for political reasons (because he was from the South) not because Kennedy really trusted him.

Robert Kennedy was JFK's Attorney General and brother.  The two brothers were close.  Sorenson did not really have a specific title, but was one of JFK's closest advisors.

Both McNamara and Rusk were important members of JFK's cabinet.  McNamara was Secretary of Defense while Rusk was Secretary of State.

So it depends on what your book/teacher thinks.  RFK and Sorenson were personally closer to JFK.  McNamara and Rusk had more important titles.  So which pair was more important?  It's a subjective matter.