Answer:
See the answer below
Step-by-step explanation:
Only one manipulated variable should be present when performing an experiment so as to be able to isolate the effects due to the changing of that variable alone.
When more than one variable is manipulated, it becomes difficult to determine which of the manipulated variables is producing the observed effects on the experimental subjects. Thus, the manipulated variable is the variable on which measured variables during the course of an experiment depends.