Megha conducted an experiment to find out the requirements
for photosynthesis. She subjected the plants to different
conditions as shown in the table below. Study the table
and use it to answer the question.
Which of the following variables should be kept
constant to conduct a fair test?
(i) Type of plant
(ii) Amount of soil
(iii) Size of pot
(iv) Type of soil
A i and ii only
B ii and iv only
C i, ii and iii only
D All of the above