The 17th day of a month is Saturday. The first day of that month was
(A) Monday
(B) Tuesday
(C) Wednesday (D) Thursday
(E) Friday
Since the 17th day of the month is a Saturday and there are 7 days in a week, then the previous Saturday was the $17-7=10$ th day of the month and the Saturday before that was the $10-7=3$ rd day of the month.

Since the 3rd day of the month was a Saturday, then the 2nd day was a Friday and the 1st day of the month was a Thursday.

ANSWER: (D)