After it was discovered, astronomers predicted Uranus's orbit using Newton's laws of motion and gravity, which had worked extremely well for all of the other planets. To their surprise, they found that their observations of Uranus's motion through the sky did not match their predictions. Which of the following would be the most logical next step?

Choose one:
A. Check for other previously undiscovered factors that might alter Uranus's orbit while still allowing it to obey Newton's laws of motion and gravity.
B. Newton's laws of motion and gravity must be modified to match the data.
C. Newton's laws of motion and gravity have been falsified, so they should be scrapped in favor of a completely new hypothesis.
D. If the data doesn't match Newton's laws of motion and gravity, then the data must be bad, so this finding should be disregarded.

The Answer is A) Check for other previously undiscovered factors that might alter Uranus's orbit while still allowing it to obey Newton's laws of motion and gravity.

Explanation:

Newton's laws of motion cannot be modified because it's a law.

Scientific laws or laws of science are statements, based on repeated experiments or observations, that describe or predict a range of natural phenomena.
Newton's laws of motion and gravity cannot be falsified given the definition of scientific laws above.

It would have made sense to discard the entire data. But from the question we know that it worked well for other planets.
So we are left with the first option: to check other factors which have not been considered, plug them into the equation, recompute and re-predict.

Cheers!