(11) The correct answer is $(A)$.

Let $m$ be the number of tiles. From the text, it follows that $m-1$ must be a multiple of 2, 3, 4, and 5. Therefore, $m-1$ must be a multiple of the least common multiple of these numbers, which is 60. Thus, it must be $m-1=60k$, with $k$ a positive integer, i.e., $m=60k+1$. Among the indicated answers, only 121 is of this type.

Question proposed by Carmelo Di Stefano.
11. Caterina is jumping along a row of tiles. Starting from the first, with jumps of 2 tiles at a time (i.e., she jumps to the $3^{rd}$, the $5^{th}$, the $7^{th}$, and so on), she reaches the last one; she turns around and, with jumps of 3 tiles at a time, returns to the first; she turns again and, with jumps of 4 tiles, reaches the last tile again; she turns once more and, with jumps of 5 tiles, returns to the first. Which of the following could be the number of tiles in the row?
(A) 121
(B) 91
(C) 90
(D) 60
(E) 31