Make a prediction: During the first trial, you will not be able to see how many people have the disease until the end. If no students are immune, how many do you think will have the disease at the end? out of 20

all 20

Explanation:

It is impossible to know how many individuals will have the disease at the end without knowing other factors such as the condition where the subjects are being held, trial specifications and safety measures, etc. Based on the information provided, the best prediction that can be made is that all 20 subjects will have the disease. This is because since none of them are immune the disease will spread between the patients/subjects through contact or testing equipment.