Which xanthine has the weakest stimulant effect?

Which of the following would be an example of functional fixedness?

a. wanting to use a rope to tie your car trunk closed and failing to realize that you could use a coat-hanger for the task b. thinking that you must solve an algebra problem the same way you solved the previous problem in the book c. beginning at the end of an analogy problem and working backwards toward the initial state d. failing to concentrate on the surface structure of a problem

Sophisticated neuroscientific tools such as the electroencephalogram, which measures electrical activity of the brain, and functional magnetic resonance imaging, which provides pictures of brain activity, have shown us that dreams

a) occur in REM sleep only. b) assist us in destroying painful memories. c) help us understand our experiences and control our emotions. d) are completely meaningless and useless.