____ uses high-frequency sound waves that are directed toward the uterus, and as they bounce off the fetus, they are converted by a computer to an image that can be viewed on a screen

A researcher wished to study the relationship between high school grades and college grades. Of the following research methods, which would be the most appropriate?

a. case study b. correlation c. experiment d. survey

__________ improves working memory efficiency and plays a role in the development and maintenance of synapses in memory areas of the brain, such as the hippocampus

a) Estrogen b) Cortisol c) Testosterone d) Epinephrine