Scientists for NASA are working on a portable farming system for future missions. It was observed, if the roots are completely submerged in water, or over-watered, the plants tended to die. What would be a simple experiment to examine this hypothesis?

a
Don't over-water a group of plants and see if they live.
b
Over-water a group of plants and compare it to an equal group of plants that are watered normally.
c
Over-water another plant and see if it dies.
d
Over-water a group of plants and compare it to one plant that is watered normally.

b

Over-water a group of plants and compare it to an equal group of plants that are watered normally.