Questions Refer to the Following Research Study

Questions refer to the following research study:
Ronda would like to assess the effects of a reading comprehension course on the scores of students. She gives a group of remedial students a reading comprehension pretest and then randomly assigns them to either the treatment group or the control group. Shortly after the treatment, she measures their reading comprehension scores again.
-Which set of results would result in Ronda being worried about maturation?

A) The treatment group improves their reading comprehension scores and the control group does not.
B) The control group improves their reading comprehension scores and the treatment group does not.
C) The treatment group and the control group both increase their reading comprehension scores.
D) The reading scores of both the treatment group and the control group stay the same across time.