Ursula works in an office. One day, her boss tells her that researchers will be in the office to observe productivity. Because she knows she is being observed, Ursula finds that she is working harder than she normally does. What is this an example of?
a. the placebo effect.
b. the Heisenberg principle.
c. a single-blind study.
d. the Hawthorne effect.

D.

Explanation:

The Hawthorne Effect was developed by researcher Henry A. Landsberger, in the 1950s. The effect derived its name from the place where Landsberger performed the research.

The Hawthorne Effect is a term used to refer to the ability of people of working hard and giving better performance. When a person becomes a participant in an experiment, according to this effect, the person or the participant tends to perform better and even work harder than before.

The given scenario is an example of the Hawthorne Effect, where Ursula is working harder and giving better performance when under the observation of researchers.

the above statement/question is (true);

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