Find the missing (?) in the series
AB, CE, FI , ?, OT
A. JM
B. GK
C. HO
D. JN

Options

A. D
B. A
C. C
D. B

Answer

To find the missing term in the series AB, CE, FI, ?, OT, we can analyze the pattern of the letters in each pair.

1. **Identify the first letters of each pair:**
- A (1st letter)
- C (3rd letter)
- F (6th letter)
- ? (unknown)
- O (15th letter)

The sequence of the first letters is: A, C, F, ?, O.

2. **Determine the pattern in the first letters:**
- From A (1) to C (3) is an increase of 2.
- From C (3) to F (6) is an increase of 3.
- To find the next letter after F (6), we can add 4:
- 6 + 4 = 10, which corresponds to the letter J.
- From J (10) to O (15) is an increase of 5.

3. **Identify the second letters of each pair:**
- B (2nd letter)
- E (5th letter)
- I (9th letter)
- ? (unknown)
- T (20th letter)

The sequence of the second letters is: B, E, I, ?, T.

4. **Determine the pattern in the second letters:**
- From B (2) to E (5) is an increase of 3.
- From E (5) to I (9) is an increase of 4.
- To find the next letter after I (9), we can add 5:
- 9 + 5 = 14, which corresponds to the letter N.
- From N (14) to T (20) is an increase of 6.

5. **Combine the results:**
- The missing pair is J (for the first letter) and N (for the second letter), which gives us the pair "JN".

Thus, the missing term in the series is **JN**.

**Final Answer:** D. JN