Answer:
Because each subject in an experiment has to have equal conditions to ensure the most accurate results. And water temperature is known to impact plant growth. An experiment using different water temperatures is a terribly inaccurate experiment.
The RNA (ribonucleic acid) and the associated proteins forms the ribosomes. These ribosomes are the site of protein synthesis in a cell. Inside the stained cell nucleus, the nucleolus part of the cell can be seen. The nucleolus is the part where the all the ribosomes of the cell are assembled.
Hence, the answer is 'nucleolus'.
