The square root of the sum of the digits in the square of 121 is
A) 4
B) 3
C) 6
D) 9

Hint:
 First, we will find the square of the given number and then add the digits of that square. Then we will find the square root of the obtained sum to find the required value.

Complete step by step solution:
We are given that the number is 121.
We will find the square of the number 121.

\[
  {\left( {121} \right)^2} = 121 \times 121 \\
   = 14641 \\
 \]
Adding the digits of this square, we get
\[1 + 4 + 6 + 4 + 1 = 16\]
Taking the square root of this value, we get
\[\sqrt {16} = 4\]
Thus, the square root of the sum of the digits in the square of 121 is 4.

Hence, option A is correct.

Note:
In this question, students should know that the square root of a number is a value that, when multiplied by itself, gives the number. This problem is really simple, students must follow the steps in order to find the required value. The square of the number 121 can easily be calculated by multiplying 121 by itself.