How does the spinal cord work with other systems to keep the body heathly (3 examples)

If birth rates fall below the replacement level, then a country is in which stage of demographic transition? a. urbanization/industrialization b. mature industrial c. postindustrial d. pre-modern

During the first month of development, how many layers of cells make up the embryo? a. 1 b. 2 c. 3 d. 4

True or false: a person who practices delayed gratification is taking a step towards his or her health.