A group of scientists believes that a pigment found in red vegetables helps cells to live longer. They test their theory by injecting this pigment into live cells growing in a test tube. After two days, the scientists count the number of healthy cells in the test tube and compare the results to a tube of cells that did not receive an injection of this pigment. What is the limitation of this experiment?

Which is the best hypothesis for the scientific question "how does light intensity affect the rate of photosynthesis"? a) light intensity, co2 concentration, and temperature are factors that determine the rate of photosynthesis.b) light intensity has no effect on the rate of photosynthesis.c) if the distance between the source of light and the plant is increased, the rate of photosynthesis will decrease.d) light intensity has an impact on the rate of photosynthesis.