In this case, we'll have to carry out several steps to find the solution.
Step 01:
Data:
time of day of watering plants vs growth rates
Step 02:
method of collecting data:
we must analyze the options to find the solution.
sample survey ===> FALSE
observational study ===> observes individuals and measures variables of interest but does not attempt to influence the responses. TRUE.
experiment ===> FALSE
The answer is:
observational study