I don't understand this. Plz help

Creation of an unnaturally uniform sample to represent a diverse populationcan be avoided by: a. including only willing b. asking another scientist for .c. choosing only identical participants. d. selecting individuals at random.

Which statement best describes a typical difference that could be found between the "analysis" and "conclusion" sections of a lab report? a) only the "conclusion" describes errors that occurred during the experiment, and only the "analysis" section suggests further research. b) only the "analysis" section includes specific data comparisons, and only the "conclusion" section suggests further research. c) only the "analysis" section discusses whether the original hypothesis was supported, and both sections include graphs of data. d) only the "conclusion section discusses whether the original hypothesis was supported, and both sections suggest further research.(the answer is b i just took the test)

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.