Proper measurement units should be chosen based on the object's scale; feet or meters for an elephant, kilometers for the moon distance, millimeters for a grain of salt, and miles or kilometers for a marathon.
To determine the most reasonable measurement for objects such as the height of an elephant, the distance from Earth to moon, width of a grain of salt, and the distance of a marathon, it's important first to conceptualize the size of these objects. Once visualized, it becomes clear that different units of measurement are applicable based on the scale and use case.
For the height of an elephant, feet or meters are reasonable, as they are typically around 8 to 13 feet tall. The distance from Earth to the moon is best measured in astronomical units or kilometers, as it is approximately 384,400 kilometers. A grain of salt is quite tiny, so millimeters would be the most suitable unit. Last, the distance of a marathon is commonly measured in miles or kilometers, with a marathon being 26.2 miles or 42.195 kilometers.
Conclusion: Proper selection of measurement units is crucial for accuracy and comprehension in various contexts, from everyday objects to astronomical distances.