Concept:After the suggestion form "Let's", the correct question tag is always "shall we?"
Explanation:"Let's" is the contracted form of "let us".
It is used to make a suggestion that includes the speaker and the listener.
For such suggestions, grammar requires the question tag "shall we?"
This tag invites the listener to agree with the suggestion.
Example: "Let's go to the library, shall we?"
Tags with "may we", "can we", or "must we" are wrong here.
Those tags suggest permission, ability, or compulsion, not shared action.
Thus, "shall we?" is the only option that matches the structure and meaning of "Let's...".
Answer:B. shall we