Scientists were conducting a multiyear study on the effectiveness of a new drug for long-term memory loss. They gave some of the test subjects the new drug to find out if it improves their long-term memory
Which is a possible limitation of this study?
O Test subjects may want to participate in additional experiments.
O Test subjects may find that the drug is not effective.
O Test subjects may get bored and want to quit early.
O Test subjects may have full-time jobs.