Final answer:
The number of craters on the surfaces of solid bodies in the solar system can be used to estimate the age of those surfaces. The more craters a region has, the older it is likely to be. This is because the rate of impacts in the solar system has been consistent over time.
Step-by-step explanation:
The number of craters on the surfaces of solid bodies in the solar system provides important clues about the age and evolution of those surfaces. By counting the number of impact craters, astronomers can estimate the length of time a surface has been exposed. This technique works because the rate at which impacts have occurred in the solar system has been roughly constant over billions of years.
The more heavily cratered terrain on a planet or moon is generally older, indicating that more time has elapsed since the region was last 'swept clean' by ongoing lava flows or other processes. This means that the number of craters is roughly proportional to the age of the surface being examined.
Therefore, the correct answer is (c) is roughly proportional to the age of the surface we are examining.