Answer:
The correct option is <u><em>option a. an extra variable that could explain result differences between groups.</em></u>
Step-by-step explanation:
Confusion variables, also called third variables, are variables that the investigator did not control or did not eliminate and that damage the internal validity of an experiment, that is, the degree to which the results are valid.
The dependent and independent variables are the two main variables of any experiment or investigation. The independent is one that changes or is controlled to study its effects on the dependent variable. The dependent is that variable that is investigated and measured.
Confusion variables may cause the investigator to analyze the results incorrectly. The results may show a false correlation between dependent and independent variables.
So <u><em>the correct option is option a. an extra variable that could explain result differences between groups.</em></u>
This is because this additional variable that was not controlled or taken into account during the experimental study modifies the result. And the other groups that conducted the experiment and took into account the variable will have different results because they take into account other independent variables.
