Bai is conducting a study on learning. when she manipulates an independent variable, it is possible that some other factor, such as noise in the hall, can affect learning in one of the groups but not in the other. this possibility reflects the presence of:

a) random assignment
b) a confound
c) selection bias
d) a dependent variable

The answer is : b) a confound

Step-by-step explanation:

While manipulating, is possible that some factors like noise in the hall, can affect learning in one of the groups but not in the other.

This possibility reflects the presence of a confound.

We can define a confounding variable as an external influencing factor which results in bringing changes in the effects of a dependent and independent variable.

This variable changes the outcome of an experiment and produces useless results.