2
7
4
9
Answer is Right!
Answer is Wrong!
The answer is $\boxed{4}$.
The missing number is the number that completes the pattern $1, 2, 4, 7, 11, 16, 22, 29, \boxed{38}$. This is a Fibonacci sequence, where each number is the sum of the two preceding numbers.
Option A, 2, is not in the Fibonacci sequence.
Option B, 7, is in the Fibonacci sequence, but it is not the missing number.
Option C, 4, is the missing number.
Option D, 9, is not in the Fibonacci sequence.