Hi abhasjha,

This SC can be solved by either focusing on some rather specific verb rules OR by focusing on the "intent" of the sentence. I chose the second option, which allowed me to quickly eliminate all 4 wrong answers.

1) Intent: Experiments, by definition, are about cause-and-effect. For example, if you experiment by taking a diet drug, then how much weight will you lose? The experiment is run to investigate the EFFECT. This SC describes a "series of experiments....." There's only one answer that properly phrases this idea.

Final Answer: B

As far as the verb issues involved, we know that we're in the past (the reference to "the mid-1920s" and the verb "was"), so we need a verb that properly describes the action. From the structure of the sentence, it seems that there were experiments that took some time to run. It wasn't one experiment at one point in time, it was multiple experiments that took awhile to run. The verb "investigating" defines the activity that was taking place. These isolated experiments were also likely meant to define what "would" happen to other workers' performances given certain conditions. Each of these verbs appears in the correct answer.

GMAT assassins aren't born, they're made,
Rich