Four-letter clusters: first letter fixed, others move +3, +5, +7

The same question, asked 2 times: 14 Sep 2025 S1*, 15 Sep 2025 S1. Every wording below, oldest first.

Try each one first, then open its answer.

Question 1
14 Sep 2025 S1
7 $Select the letter-cluster from among the given options that can replace the question mark (?) in the following series: D A F H, D D K O, D G P V, D J U C, ?$
Tap an option to check your answer.
Question 2
15 Sep 2025 S1
3 $Select the letter-cluster from among the given options that can replace the question mark (?) in the following series: H L P T, H O U A, H R Z H, H U E O, ?$
Tap an option to check your answer.