Choose the main idea of the textbook excerpt.
What Is an Adult?
Age
Body
Brain
Responsibilities
What Is an Adult?
A.
Another way to define an adult is by the person's body. An adult is a person who is grown and can have children. This is a physical definition of an adult. According to this definition, a 16-year-old is usually an adult.
B.
A person becomes an adult at age 18.
C.
There are different ways to define an adult.
D.
Teenagers don't always think or act like adults.