A student measures $V$ and $I$ for a conductor at constant temperature and finds that the ratio $V/I$ remains the same for all observations. What does this indicate?

The underlying principle is that an ohmic conductor has a constant resistance at constant temperature, so $R = V/I$ remains constant. 1. If $V/I$ is the same for every reading, then the resistance does not change from one observation to another. 2. That means $V$ is directly proportional to $I$, which is exactly the condition expressed by Ohm's law. 3. Zero resistance would require $V=0$ for finite current, which is not implied here. 4. If current were independent of voltage, the ratio $V/I$ would not generally remain constant as $V$ changes. So the constant value of $V/I$ is evidence that the conductor obeys Ohm's law.