The present ages of a mother and her son are in the ratio of 6 : 1. When the son becomes as old as his mother now, then the ratio of his father's age to his mother's age is 13 : 11. When the son becomes as old as his father now, then the sum of the ages of the father and son will be 115 years. The present age of the father is:

A

40 years

B

45 years

C

42 years

D

44 years