Final answer:
The British captured New York City in 1776, making it their base for most of the war. They also took Philadelphia in 1777 and Charleston in 1780 after a siege. Therefore, the correct option is A.
Step-by-step explanation:
The British captured several cities during the Revolutionary War, but New York City was captured in 1776 and served as the base for British operations for most of the war. After taking New York City, the British captured Philadelphia in 1777 and occupied it during the winter of 1777-1778. However, in April 1780, they managed to lay siege to Charleston, which resulted in the largest American loss during the entire war after a six-week siege. Despite these occupations, the British strategy to isolate New England failed after the Battle of Saratoga.