____ occurs when a conditioned response that had been extinguished reappears.

What is the primary reason why surgical treatments for psychological disorders are only used for the most severe psychological disorders that do not respond to other forms of treatment?

A) Surgery is too expensive for most people to afford. B) Surgical techniques are generally ineffective in treating psychological disorders. C) Performing surgery has health risks and can potentially have unintended consequences. D) Modern psychosurgery usually results in intellectual impairment.

Which of the following are key components of the human immune system?

A) The liver and kidneys B) The thymus gland and the bone marrow C) Neurotransmitters and hormones D) The pancreas and the liver