Jeremy is testing if certain levels of a new experimental drug he designed can improve immune functioning. He recruits participants for a clinical trial and randomly assigns them to either a treatment group, in which they receive the drug, or a control where they receive a placebo. After several weeks, he measures the differences between the groups’ immune functioning via blood test. Jeremy announces that the drug group had better immune functioning after the trial and claims that his drug was effective. Though the immune functioning between groups was different, that difference was not statistically significant. Assuming that Jeremy’s drug is effective, which type of validity might be insufficient for this study?
a. statisticalb. internalc. externald. construct

This experiment results show that the drug effect on patients was effective improving their immune functioning so external validation would be sufficient for this study.

Statistical information shows that the difference between the treatment group and the control group wasn't significant but still shows the improvement on immune system and effectiveness in Jeremy's test.

The drug improved the participants immune functioning as it claimed it would so costruct validation would be sufficient.

We cannot be sure that the drug stablishes a trustworthy cause and effect relation between treatment and outcome on patients and alternative explanations can be found since there was an improvement on the control group immune system as well.

Internal validation requires a trustworthy cause and effect relationship between treatment and outcome stablished by the experiment so it isn't sufficient for this study.