Well,
The distance from the earth to the moon, FYI, is over 200,000 miles. Â That is a LONG distance. Â We are trying to find a reasonable unit of measurement.
What do we mean by "reasonable?" Â We mean that that unit should be able to express the distance as a number that is not huge or tiny. Â In other words, we want it to be as close as possible to 1.
mm, or millimeters, is a tiny unit. Â It is not reasonable.
cm, or centimeters, is also a tiny unit. Â It also is not reasonable.
m, or meters, is also a relatively small unit. Â It also is not reasonable.
km, or kilometers, is the largest of the four. Â In km, the distance from the earth to the moon is about 363,000 km. Â That's not too bad.
However, if these weren't the only options, I would choose Mm, or megameters, which would put the distance at 363 Mm.
The correct option is D.