Answer:
Passage with highlighting group, passage without highlighting group
Step-by-step explanation:
A researcher randomly assigns participants to read a passage in a book with or without highlighting in the passage. Differences in comprehension are compared between groups. The passage with highlighting group is the experimental group and the passage without highlighting group is the control group in this example.
The group that is subject to the treatment is the experimental group, while the group that is not subject to the treatment is the control group.