Read the given data and select the correct option for the following questions.
Raman carried out an experiment to find out how fast water can pass through four different types of soil. He put each type of soil in four pots with equal sized holes at the base and placed separate dishes at their bottom to collect water. He poured water in them one by one, and used a stopwatch to record the time taken for water to reach the level he had marked same in each dish. His recording is given in the table as shown below.
What factors should Raman keep the same to ensure a fair test?
(i) The amount of soil
(ii) The size of the pot
(iii) The shape of the dish
(iv) The amount of water
A (iii) and (iv) only
B (i) and (ii) only
C (ii), (iii) and (iv) only
D (i), (ii), (iii) and (iv)
How can it be a fair test if the amount of water varies