A. The only difference in the shown diagram is the temperature.
In setup 1, the temperature is 20 degree and in the setup 2, the temperature is 15 degree.
So, the scientists must be studying the effect of temperature in this controlled experiment, where temperature is variable.
The habitat of the lily plant is tropical, which have a mean temperature of 18 degree Celsius. So, the scientist must be studying the effect of low temperature on lily.
The possible hypothesis could be, The lily could survive in slightly lower temperature, if proper amount of light and other nutrients are available.
B. The replication of the experiment is very important to see the validity of the result obtained, it also reduces the variability in result and avoid any preset ideas.
