Explanation:

- In the given set (56, 12, 672):

- 56 multiplied by 12 equals 672.

- Option 1 (17, 13, 426):

- 17 multiplied by 13 equals 221.

- Option 2 (15, 18, 478):

- 15 multiplied by 18 equals 270.

- Option 3 (14, 21, 294):

- 14 multiplied by 21 equals 294.

- Option 4 (16, 16, 326):

- 16 multiplied by 16 equals 256.

Each option was checked by multiplication and matched with the original rule. Option 3 follows the same pattern as the original set.