A mineral supplement designed to prevent the flu was given to two groups of people during a scientific study. Dosages of the supplement were measured in milligrams per day, as shown in the table below.
Supplement Dosages
Dosage
Group
(mg/day)
A
100
B
200
After 10 weeks, neither group reported a case of the flu. What is a procedure that would have made the outcome
of this study more valid?
A) test the supplement on both groups for 5 weeks instead of 10 weeks
B) test a third group that does not receive the supplement
C) test a third group that receives 150 mg the supplement
D) test only one group with 200 mg of the supplement

the correct answer in apex is tissue development, i know because i just had this question

the potatoes have high sugar concentrations and although these potatoes were different we could seethe effects that their sugar concentrations had in different environments. for example, the potatoes in sample a, were placed in pure water. this created a hypertonic environment and caused the potatoes to draw in water from its surroundings. we saw the opposite happen with the potatoes in sample b when placed in the sodium chloride solution. the potatoes in this case were in a hypotonic solution and therefore lost water to their surroundings.