Liberalism and conservatism are both rooted in principles found in the political philosophy of

John Locke

Explanation:

In the past, John Locke was a prominent supporter of  establishing free markets, limited power of government , and personal responsibility for the citizens who want to achieve success.  At that time, the group of people who adopted these views are belonged to the classical liberal group.

As the time progress, the liberal groups try to put more emphasize on social issues. Because of this, the modern day parties that hold that exact same view now belong in the conservative group.

answer; researchers typically cannot control people's sexual behaviors as would be necessary in an experiment;

the answer is true!