Final answer:
Cultural transmission is an exchange of cultural features between groups in contact over time.
Step-by-step explanation:
An exchange of cultural features between groups in firsthand contact over a long period of time is known as cultural transmission. This refers to the way people learn the values, beliefs, and social norms of their culture. It involves the sharing and spreading of culture, such as ideas, language, food, art, and technology, from one group to another.