Select the option that will replace the question mark (?) in the given series.

C2, E3, G5, I8, K13, M21, ?

The correct option is O34.

To determine the term that replaces the question mark (?), we can analyze the given series by breaking it down into two parts: the letter pattern and the number pattern.

1. Letter Pattern:
Let's examine the positions of the letters in the English alphabet:
C = 3
E = 5
G = 7
I = 9
K = 11
M = 13
We can see that each consecutive letter moves forward by 2 positions in the alphabet:
3 + 2 = 5 (E)
5 + 2 = 7 (G)
7 + 2 = 9 (I)
9 + 2 = 11 (K)
11 + 2 = 13 (M)
Following this pattern, the next letter position is:
13 + 2 = 15, which corresponds to the letter O.

2. Number Pattern:
The series of numbers is: 2, 3, 5, 8, 13, 21, ?
Starting from the third number, each number is formed by adding the two preceding numbers (Fibonacci series pattern):
2 + 3 = 5
3 + 5 = 8
5 + 8 = 13
8 + 13 = 21
Following this pattern, the next number is:
13 + 21 = 34.

Combining the letter and number together gives O34.