Rahul wanted to find out how polluted water affects the survival of guppies. Which of the following set-ups should he use to conduct a fair test?
A a and b only
B b and c only
C a and d only
D c and d only
Please explain the answer.
Rahul wanted to find out how polluted water affects the survival of guppies. Which of the following set-ups should he use to conduct a fair test?
A a and b only
B b and c only
C a and d only
D c and d only