From the given image_7f89a2.png, find the odd one out in the series: A1, C9, E25, G49, I89.

Let's analyze the relationship between the letter and the number in each alphanumeric term:
* A1: Position of A in the English alphabet is $1$. The number part is $1^2=1$.
* C9: Position of C in the English alphabet is $3$. The number part is $3^2=9$.
* E25: Position of E in the English alphabet is $5$. The number part is $5^2=25$.
* G49: Position of G in the English alphabet is $7$. The number part is $7^2=49$.
* I89: Position of I in the English alphabet is $9$. The number part should be $9^2=81$. However, the term given is I89.

Therefore, I89 is the odd one out.