Find the missing character?

J
U
D
A

The missing character is J.

The sequence is a simple alternating repetition of the letters A and J. The first letter is A, the second letter is J, the third letter is A, the fourth letter is J, and so on.

Option A: J is the correct answer.

Option B: U is not the correct answer because it is not in the sequence.

Option C: D is not the correct answer because it is not in the sequence.

Option D: A is not the correct answer because it is already in the sequence.