Answer:
Experiment
Explanation:
Base on the scenario been described in the question, where Mrs. Reynolds has many (over a hundred) houseplants of many different types including philodendrons, ferns, spider plants, cacti, tomatoes, pineapples, this is a typical example of experiment .
An experiment is a procedure carried out to support, refute, or validate a hypothesis. Experiments provide insight into cause-and-effect by demonstrating what outcome occurs when a particular factor is manipulated