Answer:
a hypothesis
Step-by-step explanation:
A hypothesis is a statement that is supposed or assumed before conducting any experiment. It is the assumption that is made on the basis of certain knowledge and controlled evidence in the initial time of the experiment. The initial assumption helps in taking the experiment or the investigation further. The truth is not ascertained in the initial phase rather the completion of the investigation is necessary to make a hypothesis turn into a theory.
In the given situation, the statement given is a hypothesis because the use of the warm water for the growth of the plants is the assumption made with respect to the metabolism effect on the humans.