Question

Which is the fairest way to take a representative sample from a population? A. choosing participants who will ensure that study results will support the hypothesis B. carefully selecting specific subjects who meet one’s criteria from the population C. ensuring that every subject in the population has an equal chance to be selected D. using a survey to screen out participants who may interfere with other subjects

Answer 1

I'm pretty sure its

c. ensuring that every subject in the population has an equal chance to be selected

Answer 2

C. Ensuring that every subject in the population has an equal chance to be selected.
If you look at the Presidential Election. The national poll takes numbers from part of the population. But it doesn't represent the people that didn't get polled. So polling each county separately better represents that specific area.