a 3 - 7a - 6 এর উৎপাদক কত?

1. ক(a + 1)(a - 2)(a - 3)
2. খ(a + 1)(a + 2)(a - 3)
3. গ(a - 1)(a + 2)(a - 3)✓
4. ঘ(a - 1)(a - 2)(a - 3)