In sentence 17 (reproduced below), which of the following versions of the underlined text provides relevant, specific information that helps the audience understand the study? The robots—while the children were able to do the task correctly when they were absent—unanimously gave an incorrect answer first.

A. (as it is now)

B. less influential when the experiment was repeated with adult subjects

C. programmed to glance at one another, as though considering the question together

D. which may be replaced with more impressive-looking robots in future experiments

E. a variation on an experiment conducted with only human participants