The participants in philip zimbardo's simulated prison study:

a. were assigned the roles of prisoner or guard on the basis of their personality test scores.
b. found it very difficult to play the role of prison guard.
c. were so endangered by their role-playing experience that the study was discontinued.
d. became a cohesive unit when they pursued superordinate goals.

C. were so endangered by their role-playing experience that the study was discontinued

Explanation:

In 1973, Philip G Zimbaro conducted an experiment to investigate the brutal behavior of the American prison guards because of their sadistic tendencies. Zimbardo used college students to act prisoners or guards in a simulated prison environment. But the brutalities on prisoners increased so high that Zimbardo had to discontinue the experiments only after six days.

question - in 1827, john walker, a druggist in a small english town, tipped a splint with sulphur, chlorate of potash, and sulphid of antimony, and rubbed it on sandpaper, and it burst into flame. the druggist had discovered the first friction-chemical match, the kind we use to-day. it is called friction-chemical because it is made by mixing certain chemicals together and rubbing them. although walker's match did not require the bottle of acid, nevertheless it was not a good one. it could be lighted only by hard rubbing, and it sputtered and threw fire in all directions. in a few years, however, phosphorus was substituted on the tip for antimony, and the change worked wonders. the match could now be lighted with very little rubbing, and it was no longer necessary to have sandpaper upon which to rub it. it would ignite when rubbed on any dry surface, and there was no longer any sputtering. this was the phosphorus match, the match with which we are so familiar. according the paragraph what was the benefit of the new phosphorus match? it burst into flame when rubbed on sandpaper. it was made by mixing chemicals. it could be ignited on any dry surface. it threw fire in all directions.

answer - matches required natural chemicals