When Charmaine Was 10 Years Old,she Completed the Original Stanford-Binet

When Charmaine was 10 years old,she completed the original Stanford-Binet Intelligence Scale.She answered all the questions that a typical 6-year-old would answer,but none of the questions a typical 7-year-old would answer.What is Charmaine's mental age based on this information

A)  6 years 
B)  7 years 
C)  10 years 
D)  6/10 years