Biology Forums - Study Force

A research study indicates that one group of teachers was trained to bring each lesson to a form of clear closure. A comparable group of teachers received no training. Of the following, which is the most likely way the researchers made sure the two groups of teachers were comparable?
A) They randomly assigned teachers to the two groups before training the teachers.
B) They conducted their research in two schools that had students with comparable backgrounds.
C) They tested the teachers to determine their levels of intelligence and knowledge of the content they taught.
D) They interviewed each of the teachers before training one group.

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