Insert the missing number: 7, 10, 9, 12, 11, _____?

14 and 13

12 and 10

15 and 14

None of these

The sequence alternates between adding 3 and subtracting 1. Following this pattern:
7 (+3) → 10 (-1) → 9 (+3) → 12 (-1) → 11 (+3) → 14 (-1) → 13.