Explanation:

- Let's assign:

- Amit + Sunil: 1 work in 9 days ? Work/day = 1/9

- Sunil + Dinesh: 1 work in 12 days ? Work/day = 1/12

- Amit + Dinesh: 1 work in 18 days ? Work/day = 1/18

- Let Amit = A, Sunil = S, Dinesh = D

- So,

- (A+S) = 1/9

- (S+D) = 1/12

- (A+D) = 1/18

- Add all:

- (A+S) + (S+D) + (A+D) = 1/9 + 1/12 + 1/18 = (A+S+D) + (A+S+D) = 2(A+S+D)

- Find the LCM of 9, 12, 18 = 72

1/9 = 8/72, 1/12 = 6/72, 1/18 = 4/72

Sum = 8/72 + 6/72 + 4/72 = 18/72 = 1/4

- So, 2(A+S+D) = 1/4 ? (A+S+D) = 1/8

- Thus, together they finish the work in 8 days.

- Correct Option:

Option 2: 8 days

- Other options (12, 14, 16 days) are incorrect.