The correct option is D 23D
In the given pattern following points can be observed.
1. The numbers are decreasing. The next number in the pattern will be 1 less than the previous one.
2. The Alphabets with the numbers are in increasing order, i.e, A, B, C, ....
Therefore based on the above observation
1. Number will be 23
2. D will be the alphabet
23D will come in the blank.