10) The manager of a restaurant with a capacity of 600 seats does not remember how many people he served during a large collective lunch. However, he remembers that if he tried to seat them at tables of 3, exactly one person would be left out, and the same thing happened when seating them at tables of 4, 5, or 6. However, when seating them at tables of 7, no one was left out. How many people were there?
(A) 61
(B) 121
(C) 175
(D) 301
(E) 574.
10) The answer is (D). 301 is the only one among the indicated numbers that is divisible by 7 and gives a remainder of 1 when divided by $3,4,5,6$.