Complete the following series.
7D, 15H, 23L, ?

Given: 7D, 15H, 23L, ?​​

Logic: Number is increasing + 8 and letter is increasing + 4place.

For, number

7 + 8 = 15, 15 + 8 = 23, 23 + 8 = 31

For, letter

D + 4 = H, H + 4 = L, L + 4 = P

So, the missing term is 31P.

Thus, correct option is (d).