What measurement unit is used to convert feet to chains?

To convert feet to chains, it is important to note that one chain is defined as 66 feet. This measurement is part of the surveyor's units and is used in land surveying, particularly in the United States. A chain consists of 100 links, with each link measuring 7.92 inches; when you multiply the length of a chain by the number of feet in it (66), you verify the equivalence.

This allows surveyors to easily translate land measurements into a more manageable unit without needing to deal with larger numbers. The other options presented do not correspond to the length of a chain. For instance, 5280 feet corresponds to one mile, which is not relevant for the conversion to chains, and the other options—100 feet and 360 feet—do not accurately represent a chain's length either. Thus, the choice that correctly identifies the unit used for converting feet to chains is indeed 66 feet.