Explanation:

To find out how many days A, B, and C will take to finish the job together, let's calculate their combined work rate:

1. Work Rates:

- A's rate: 1 job in 10 days = 1/10 job per day.

- B's rate: 1 job in 15 days = 1/15 job per day.

- C's rate: 1 job in 6 days = 1/6 job per day.

2. Combined Work Rate:

- Total rate = 1/10 + 1/15 + 1/6 = 1/3

3. Time to Complete the Job:

- Since they complete 1/3of the job in one day, the whole job will take them 3 days.

Option 2 (3 days) is the correct choice