Final answer:
The negative control for the investigation in question is option d) Omitting the Test Substance.
Step-by-step explanation:
The negative control for the investigation refers to a control group that does not receive the treatment being tested. In this case, the investigation involves testing the effects of certain actions on a reaction. The action that will provide a negative control is option d) Omitting the Test Substance.
By omitting the test substance, the investigator can compare the results of the reaction in the absence of the substance to determine the specific effects of the substance being tested.