A, B, and C working alone can finish constructing a house in 6, 8, and 12 hours respectively. A starts alone and works for 1 hour. He is then joined by B and they work together for 1 hour. Finally C joins them and they all work together to finish the work. If they start working at 9 am, at what time will they finish?	Choose the correct choice from the following
A) 11:36 am
B) 11:48 am
C) 12:05 pm
D) 12:27 pm
E) 12:43 pm
A completes 1/6 of the job each hour.   B completes 1/8 of the work each hour.   C completes 1/12 of the work each hour.   A completes 1/6 of the work in the first hour.   Working together, A and B complete another 7/24 for a total of 11/24.   Working together, A, B, and C can complete 9/24 of the work each hour.   To complete 13/24, the time required is (13/24) / (9/24) = 13/9 hours.   The work will be completed at 12:00 plus 4*60/9 minutes which is about 12:27 pm.   The answer is 12:27 pm.
<result>D</result>
A, B, and C working alone can finish constructing a house in 6, 8, and 12 hours respectively. A starts alone and works for 1 hour. He is then joined by B and they work together for 1 hour. Finally C joins them and they all work together to finish the work. If they start working at 9 am, at what time will they finish?