Answer:
A) The emotional or neutral word list
Step-by-step explanation:
An independent variable in a research study, is the variable which when manipulated or changed, brings a change or effect on the dependent variable that is measured. In order words, the independent variable is the variable that is being manipulated, especially in an experimental research design.
In the experiment conducted by Dr. Jeffries, as we can see in the question above, the variable that is manipulated here is the "emotional or neural word list". Therefore, the independent variable in Dr Jeffries' study is the emotional or neutral word list.