The theory that states that motor development is a dynamic process of active coordination of multiple systems within the infant in relation to the environment is called

A) dynamic systems theory.
B) dynamic coordination theory.
C) ecological validation theory.
D) reciprocal systems theory.

The theory described in the question is known as dynamic systems theory. This theory emphasizes the dynamic and complex interaction between multiple systems within the infant and the environment that contribute to the development of motor skills. It rejects the idea that motor development is a simple, linear process and instead suggests that it is a constantly evolving and adaptive process. The other answer choices (B, C, and D) are not associated with this theory.