Answer: The correct option is (A) 3x + 5.
Step-by-step explanation: We are given to select the correct factor of the following quadratic expression :
To factorize the given expression, we must find two numbers whose sum is 21 and product is 90.
The factorization of the given expression is as follows :
Therefore, the required factors of the given expression are (3x + 2) and (3x + 5).
Thus, the factor (3x + 5) is the correct one.
Hence, option (A) is CORRECT.