Letter A is correct.
Implicit memory is one type of long-term memory that is considered to be unconscious or automatic. Procedural memory, which is a subset of implicit memory, makes it possible for us to perform physical activities (such as running, riding a bike or walking) without even thinking about it. Other good examples of implicit memory are: buttoning a shirt, driving a car, brushing your teeth and recalling rules of a simple and familiar game like "Dominoes".
