Which option indicates why the results of the study in the following scenario should be questioned? Behavioral scientists tested the ability of normal adult humans to concentrate on simple tasks when a television was turned on in the background. As a control, they used performance on the same test when the television was off. The experiment included 20 university students as a sample. The researchers have concluded that the presence of noise from television has an impact on the ability to concentrate.

The study may have introduced bias in the tasks performed on the test.

The study may have used unclear terms in its thesis.

The study may have had too small a sample size.

The study may have excluded other relevant facts from the conclusion.