Dr. MacGiver believes that children who are not visually stimulated during the first four months of life will never develop normal visual perception. Obviously, Dr. MacGiver believes that this developmental stage is a:.
A. cognitive schema.
B. teratogen.
C. epigenetic mark.
D. critical period.

Match the item to the definition: indirect correlation, correlational research, correlational research, covary, pearson correlation coefficient, pearson correlation coefficient, direct correlation a. used to describe the relationship between two or more naturally occurring variables b. determines whether scores on the two variables covary c. whether two variables vary or change together d. denoted by the symbol "r" e. provides information about the sign (direction) and magnitude(strength) of the linear relationship. f. when the correlation is positiveg. when the correlation is negative