scientists who study the process common to all populations are called a. sociologists b. anthropologists c. community environmental d. population ecologists

Could someone me with number one you

Acell in the human nervous system whose primary function is to form myelin and the blood-brain barrier, respond to injury, remove debris, and enhance learning and memory is called a(n) cell.

Ascientist is conducting an investigation that involves water, silver, carbon dioxide, and oxygen gas which group of statements best describes all of the materials he is using in the investigation?