Shortening the time between pretest and posttest or perhaps even offering cash payments to participants in an experiment are techniques that may be used to
a. limit diffusion
b. decrease experiment mortality
c. decrease the effects of instrumentation
d. control threats to testing

By shortening the time between pretest and posttest or perhaps even offering cash payments to participants in an experiment are techniques that may be used to: B) decrease experiment mortality.

Explanation:

To understand why the decrease of experiment mortality is the correct answer we have to analyze the concept. Experimental mortality is the concept used in research methods in all sciences to say that an experiment can fail because of the abandonment from the sample being studied. This happens because there are several reasons why a person could abandon the study. Thus, reducing it could be the best way to ensure the study's success by finishing. It is strictly related to validity because if te sample drops out there will be no acceptable sample individuals to make it valid. As studies require to have a certain number of participants to be valid.

i would say b. research typically uses a variety of sources