Alice the number theorist knows the rule for testing if a numbernis divisible by 3: n is divisible by 3 if and only if the sum of the digits ofnis divisible by 3.

When Alice visits Mars, she finds that the Martians have six hands, and six fingers on eachhand, so that they count in base 36. In base 36, Alice’s divisibility test doesn’t work for testing divisibility by d= 3. But it does work for one of the d listed below. Which one?

a. 4
b. 7
c. 10
d. 11
e. 15