Spain entered the revolutionary war in 1779 to

defeat american colonies and regain florida.
defeat britain and regain florida.
defeat france and divide florida into colonies.
defeat britain and divide florida into colonies.

Spain entered the Revolutionary War in 1779 to help  defeat Britain and regain Florida.

Explanation:

The Anglo-Spanish War of 1779-1783, part of the War of Independence of the United States, was the conflict between Spain and Great Britain that resulted from the Spanish intervention in favor of the United States.

Spain, allied with France through the Pacte de Famillie, saw the Revolution of the Thirteen Colonies as an opportunity to weaken the British Empire, which had caused major losses to Spain during the Seven Years War. As a result of  this participation, Spain regained Florida back from Britain.