In the Fibonacci sequence 1, 1, 2, 3, 5, . , each number beginning with the 2 is the sum of the two numbers before it. For example, the next number in the sequence is $3+5=8$. Which of the following numbers is in the sequence?
(A) 20
(B) 21
(C) 22
(D) 23
(E) 24
Since each number in the Fibonacci sequence, beginning with the 2, is the sum of the two previous numbers, then the sequence continues as $1,1,2,3,5,8,13,21$.

Thus, 21 appears in the sequence.

ANSwER: (B)