In order for a bill to become law at the federal level, which of these must occur?

If a bill has passed in both the U.S. House of representatives and U.S. Senate and has been ratified by the President, the bill becomes a law and is enforced by the government. 

The President must approve the bill and sign it. 

(D) retrieval cue                                                                      

Explanation:

Retrieval cue: In psychology, the term "retrieval cue" is described as a prompt that assist an individual to remember different things. When an individual tends to make specific new memories then he or she ought to include a few information related to the given situation as well in which those memories are being developed so that it acts as a trigger to approach the given memories.

Retrieval cues help an individual to approach memories that are being stored in his or her long-term memory and therefore helps to carry-out those memories into his or her "conscious awareness".

In the question above, the picture served as a powerful retrieval cue.