Answer
a. law;
b. theory;
c. observation;
d. law
Work Step by Step
a. This used to be a past observation that eventually led to the prediction of the tides after every day; therefore, this is a law.
b. This has been observed and a hypothesis has been established; therefore, this is a model of nature and a theory.
c. This is simply an observation.
d. A hypothesis was established about tides which led to the prediction of tides; therefore, this is a law.
