If a Carpenter Wants to Make Sure That the Corner $17.5$

Multiple Choice

If a carpenter wants to make sure that the corner of a closet is square and measures 5 ft and 12 ft. along the walls, how long should he make the diagonal?

A) $17.5$ ft
B) $13.6$ ft
C) $16$ ft
D) $13$ ft
E) $17$ ft