Each of A,B and C need a certain unique time to do certain work. C needs 1 hour less than A to complete the work. Working together they require 30 minutes to complete 50% of the work. The work also gets completed if A and B start working together and A leaves after 1 hour and B works further 3 hours. How much work does C do per hour?

1) 16.66%
2) 66.66%
3) 50%
4) 33.33%