Answer:
a. verify that your observations are correct
c. think about what else might cause the observed discrepancy
Step-by-step explanation:
Let's begin by explaining that a law is an affirmation (something established) based on repeated long-term observation of a phenomenon that has been studied and verified.
That is: A law is present in all known theories and therefore is considered universal. In addition, a law can not be refuted, nor changed, because its precepts have been proven through various studies.
Then, based on what is explained above, Kepler's laws of planetary motion exist because they were rigorously tested and verified, therefore they can not be refuted.
So, if we have a small discrepancy between the predicted and actual positions of Uranus after using Kepler's laws, we have to verify carefully our observations again and search what might be causing that discrepancy. But we cannot assume Kepler's Laws are incorrecto or need modifications.
In addition, we cannot consider that Uranus may not be a planet, because the discrepancy is small. In fact, this discrepancy lead to the discovery of another planet, Neptune.