I’ll insert the missing terminals so that the unique derivation for the target uses:

- A2 → A3 1, so A2 ⇒ 2 1
- A8 → A3 7, so A8 ⇒ 2 7
- A10 → 8 9, to cover the “8 9” pair

Updated production rules:
rule_2: A2 -> A3 1
rule_12: A8 -> A3 7
rule_14: A10 -> 8 9