Swing States Are Important to a Presidential Candidate's General Election

Swing states are important to a presidential candidate's general election strategy because:

A) they favor one party's candidate over another, which saves the favored candidate money to campaign elsewhere
B) they provide better opportunities for fund-raising
C) they can be ignored
D) they can potentially be won by either major-party candidate
E) they are always small states, so they do not provide that many electoral college votes