To test the effect of hormones on plant growth, six potted plant seedlings of the same species were measured and then sprayed with auxin (a growth hormone). after four weeks of growth under ideal conditions, the plants were measured again. to set up a proper control for this experiment, the investigator should what do?

The investigator needs to add a negative and a positive control. The positive control can be an auxin previously tested on this plant species, and the negative control should be a NON AUXIN SPRAYED plant, it can be sprayed with disstilled water. It is importan that all these plants are exactly under the same conditions (temperature, light, etc.), but with a distance between them that does not allow crossed contamination.

Explanation: