Scenario: A laboratory study that compared learning from text in two conditions, one with underlining of important terms and one without underlining, found that the underlining group did better on factual items. Marina conducted a study with tenth-grade history students and compared one group that read a chapter with the important text underlined and one group that read a chapter without any underlining. In her study she found no effects for the underlining. Question: Marina's findings may indicate that the underlining treatment has

answer choices

a. low external reliability.

b. low external validity.

c. low internal validity.

d. low internal reliability.