Please me with the answer

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.

Control of the body is accomplished by which of the following body systems? nervous system and circulatory system endocrine and repertory system circulatory and respiratory systems nervous system and endocrine systems

Prior to the mt. st. helens eruption on may 18, 1980, satellite and topographic views of the volcano were captured. based on the topographic map of mt. st. helens, what is the contour interval if the volcano height is 2,950 m? question 9 options: 600 m 400 m 750 m 500 m