Answer: B. complex but seemingly effortless human cognition is.
Explanation: Human cognition covers the method humans use to acquire and recall knowledge. It is complex because the forms of input are varied, and the process requires several steps. When we acquire or recall knowledge we use our senses and memory. In some instances we are not even putting in any conscious effort. This applies to recalling such abilities as driving, or using language that we have mastered.
This is what happens as Sarah recognizes her friend without making an effort, her sight references her memory without making a conscious effort.
