1) Loretta goes to a clinic every 13 days for a treatment. Franco, her favorite nurse, works at the clinic only on Thursdays. Knowing that today, Thursday, Loretta went to the clinic, in how many days will she see Franco again?
(A) 14
(B) 35
(C) 53
(D) 65
(E) 91
1. The answer is $(\mathbf{E})$.

Since Loretta goes to the clinic every 13 days and Franco every 7 days, they will meet at the clinic after a number of days that is a multiple of both 13 and 7; the smallest of these numbers is the least common multiple of 13 and 7, which is 91.

[Problem proposed by A. Colesanti]