200
An investigation was carried out to determine which of three antibacterial soaps is most effective. Four petri dishes labeled A, B, C , and D were set up. The same amount and type of bacteria was added to each dish. Next, 2 mL of a different brand of soap were added to dishes B, C, and D. Then, 2 mL of water were added to dish A, instead of soap. The dishes were incubated at 37°C for 24 hours. At the end of the investigation, the amount of bacteria in each dish was determined. Dish D had the least bacteria. It was concluded that the soap in dish D was the most effective soap to use against bacteria.
Which statement best describes the validity of this conclusion?
What is
A) sample of bacteria was used in this investigation.
B) The conclusion is valid since too small
C) The conclusion is valid since the amounts of bacteria were
measured at the end of the investigation.
D) The conclusion might not be valid since the investigation was
carried out only once.