What should come in the place of the question mark (?) in the following alphanumeric series?

A1X, B4P, E25J, J100F, ?

The correct option is Q289D.

To find the next term in the alphanumeric series, we can analyze the patterns of the first letter, the middle number, and the last letter of each term separately.

1. Pattern of the First Letter:
Let us look at the English alphabetical positions of the first letters of each term:
- A is the 1st letter (position 1).
- B is the 2nd letter (position 2).
- E is the 5th letter (position 5).
- J is the 10th letter (position 10).

Let us find the differences between the consecutive positions:
- Between A and B:
$2-1=1$
- Between B and E:
$5-2=3$
- Between E and J:
$10-5=5$

The differences between the positions are consecutive odd numbers: 1, 3, and 5. Therefore, the next difference must be 7.
Adding 7 to the position of J (10):

$10+7=17$

The 17th letter of the alphabet is Q.

2. Pattern of the Middle Number:
Let us analyze the numbers in each term and relate them to the first letter's position:
- In A1X, the number is 1, which is $1^2$ (position of A squared).
- In B4P, the number is 4, which is $2^2$ (position of B squared).
- In E25J, the number is 25, which is $5^2$ (position of E squared).
- In J100F, the number is 100, which is ${10}^2$ (position of J squared).

Following this logic, the middle number of the next term should be the square of the alphabetical position of its first letter (Q, which is at position 17):

${17}^2=289$

3. Pattern of the Last Letter:
Let us look at the alphabetical positions of the last letters of each term:
- X is the 24th letter (position 24).
- P is the 16th letter (position 16).
- J is the 10th letter (position 10).
- F is the 6th letter (position 6).

Let us find the differences between the consecutive positions:
- Between X and P:
$16-24=-8$
- Between P and J:
$10-16=-6$
- Between J and F:
$6-10=-4$

The positions decrease by consecutive even numbers: -8, -6, and -4. Therefore, the next position must decrease by 2.
Subtracting 2 from the position of F (6):

$6-2=4$

The 4th letter of the alphabet is D.

Combining the first letter (Q), the middle number (289), and the last letter (D), the next term in the series is Q289D.