Donna, a Reading Specialist, Compared Reading Motivation Between Two Fifth

Donna, a reading specialist, compared reading motivation between two fifth grade classes. For one class she provided a free selection of books of their
Choice. For the other class she pre-selected the books for the students. Her
Hypothesis was that students given more choice in the library would have higher
Motivation to read. Her hypothesis was supported. Lisa, when reading her report, wondered if there were pre-existing differences between the classes that were not
Considered or if there were extraneous variables not addressed. These oversights
In Donna's work are primarily a problem with her

A) participants.
B) hypothesis.
C) design and procedure.
D) Instruments.