I'm pretty sure it was Wilhelm Wundt, sorry if I'm not right!
Answer:
SYNTACTIC
Explanation:
To illustrate the idea of critical period in learning, Dr. Kuhl in her video presentation mentioned the study of Johnson and Newport which 'summarizes a lot of literature having to do with SYNTACTIC performance in a second language and phonological performance in a second language".
The answer for your question would be : A. Gross motor skills
Gross motor skill utilize the movement from one's arms, leg, and feet to create a larger actions such as walking, jumping , or running. The fact that that infant are capable to walk is a sign of the development of Gross motor skills