Alcohol just never seemed to be an intoxicating substance for him . He could drink extensively , the strongest liquor available ( and in fact his chosen beverage was Absinthe ) , but still remain completely sober . Marijuana acted much like an energy drink would to someone else .

Generate a question about the above context.
Why is their friend able to drink so much ?
Options are:
a). They always smoke marijuana while they drink .;
b). They are used to drinking a lot of alcohol .;
c). They are a large person .;
d). None of the above choices .;