The correct answer is D.
A swing state refers to a state in American politics that could reasonably be won by either the Democratic or the Republican presidential candidate.
The opposite of a swing state is a safe state.
Because no candidate is certain to win the popular vote there, these states are targeted by both major-party campaigners, especially if the election is considered to be a close one. In the final stages of the electoral campaign, the candidates may campaign only in the swing states and concentrate heavily on campaign advertising there.
Some of the traditional swing states in the USA are: New Hampshire, Colorado, Michigan, Minnesota, Florida and Iowa.
