A group of biology students conducted a lab to study the effect of water on plant growth. They used the following procedure:

1 – Germinate nine bean seeds.

2 – Put three bean plants each into three identical pots containing the same weight and type of soil. Label the pots A, B, and C.

3 – Place pots in an area where they can receive the same amount of sunlight.

4 – Each day pour 30 mL of water into pot A, 20 mL of water into pot B, and 10 mL of water into pot C.

5 – Measure and record the height of the plants every other day for 15 days.

Recorded data:

Which was a limiting factor for this experiment?