Self-righting does not help the brain development of infants who do not have enriching environments

Even when twin studies find that monozygotic twins have higher concordance rates than dizygotic twins, it is possible these results are not due to genetics but to the possibility that

a. DZ twins are usually treated very similarly. b. MZ twins may be treated more similarly than DZ twins. c. MZ twins are easier to locate and study. d. DZ twins are more likely to live in similar environments.

Activation of the sympathetic nervous system

A) only happens if someone chooses "fight" rather than "flight". B) can have ill effects when it is sustained over time. C) helps a person relax. D) happens in response to exposure to viruses.