Mario was attempting to develop a cure for the flu. mario gave three test subjects, all sick with the flu, massive doses of vitamin c. all three subjects recovered within a week. mario concluded that massive doses of vitamin c will cure the flu. why did the scientific community deem mario's research to be invalid?

The correct answer is - there is no control group to compare results.

Explanation:

A control group is a group that is used in the experiment in order to get an accurate relation between the independent group and the dependent group. It is kept constant during the experiment.

In this clinical research, there is no control group or nothing is constant as all three subjects got the same treatment so there is nothing to compare the result with and prove its effect. So, it is not validated by the scientific community as there is nothing to compare or check with.

Thus, the correct answer is- there is no control group to compare results.