William was bullied by members of a particular ethnic group all through elementary school. Due to this experience, he perceives all members of this ethnic group to be a threat to his safety and security. William is exhibiting

Which of the following is true about scientific theories?

A) All theories are equally plausible. B) The quality of a theory cannot be measured by the number of people who believe it to be true. C) Theories are the same thing as opinions or beliefs. D) A theory is only valid if it has been proven to be true.

Positive reinforcers:

a. weaken behaviors they follow. b. are always learned. c. strengthen behaviors they follow. d. are always unlearned.