Final answer:
An amoeba does not have the ability to sense light or keep time, while a clock can. Both an amoeba and a clock exist, but they have different characteristics.
Step-by-step explanation:
To classify each characteristic as true for an amoeba, a clock, or both, we need to consider their respective traits. An amoeba is a single-celled organism that can change its shape and move using pseudopodia. It does not have the ability to sense light or keep time. On the other hand, a clock is a device that can sense light and dark and keep time. Therefore, the characteristic of being able to sense light and keep time is true for a clock, but not for an amoeba. Both an amoeba and a clock exist, but they have different characteristics.