Four-letter clusters: first letter fixed, others move +3, +6, +9

The same question, asked 2 times: 14 Sep 2025 S1*, 16 Sep 2025 S3. Every wording below, oldest first.

Try each one first, then open its answer.

Question 1
14 Sep 2025 S1
6 $Select the letter-cluster from among the given options that can replace the question mark (?) in the following series: TDGJ, TGMS, TJSB, TMYK, ?$
Tap an option to check your answer.
Question 2
16 Sep 2025 S3
4 $Select the letter-cluster from among the given options that can replace the question mark (?) in the following series: S C E G, S F K P, S I Q Y, S L W H, ?$
Tap an option to check your answer.