In an experiment, two different types of recorded music were played for neonates in adjacent nurseries in a hospital. In nursery A, classical music was played; in nursery B, rock music was played. After two weeks, it was found that the babies in nursery A cried less, suffered fewer minor ailments, and gained more weight than did the babies in nursery B.
In evaluating the validity of the conclusion suggested by the experiment above, it would be most important to know which of the following?

Question

Examsnet · Accepted Answer

Correct Answer is :  Whether the newborns in both nurseries were equally healthy and happy at the start of the experiment

GMAT Verbal Reasoning Practice Test 2