P and Q started a partnership business investing some amount in the ratio of 3:5.R joined them after 6 months with an amount equal to that of Q.In what proportion should the profit at the end of one year be distributed among P,Q and R?
A3 : 7 : 5
B6 : 10 : 5
C3 : 2 : 5
DNone of these
Please explain this answer