Explanation:

- To find when all the bells will toll together again, calculate the Least Common Multiple (LCM) of their intervals: 3, 4, 6, 7, 8, and 12 seconds.

- Step-by-step LCM calculation:

- Factors for 3: 3

- Factors for 4: 2^2

- Factors for 6: 2 × 3

- Factors for 7: 7

- Factors for 8: 2^3

- Factors for 12: 2^2 × 3

- Take the highest power of each prime factor: 2^3, 3, and 7.

- Calculate LCM: 2^3 × 3 × 7 = 168 seconds.

- Therefore, the bells will toll together again after 168 seconds.

- Options to consider:

- Option 1: 167 (Not the LCM)

- Option 2: 168

- Option 3: 176 (Not the LCM)

- Option 4: 186 (Not the LCM)