What keeps the moon from turning away from the earth

Which sentence best expresses the differing opinions of these two book reviews?

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.

Graphs you see question 5 options: the change in data over time the relationship between different dependent variables the relationship between the independent variable and the dependent variable/s the relationship between different independent variables