Answer;
D.60 million years
Explanation;
The two species shared a common ancestor 60 million years ago, if the molecules found in these two species differ by a total of six mutations.
Mutation is a sudden, random spontaneous change that occur in the genetic make up of an organism or a cell.
If one mutation occurred after 10 million years;
Then six mutations will need (6 ×10) 60 million years.