What Is True of Early Speech in Children

What is true of early speech in children?

A) More than half (65%) of children's first words comprise action verbs.
B) Early phrases such as "all gone" and "bye-bye" function as words when used continuously to symbolize the same meaning.
C) Vocabulary acquisition is generally very rapid once a child speaks their first word.
D) A child's first word typically is spoken between the ages of 18 and 20 months.