I think its B. It sounds familiar
It's important so that they know exactly where the disease started. Knowing who patient zero is helps them to identify who that person interacted with. From there, they can determine where the disease spread to. This will aid them in stopping the disease before it spreads any further.
D the expansion of their territory
Lunar maria (plural form of the Latin word mare, which means sea) are dark surfaces that can be found all over the moon (17% of the Moon is covered in them) that have been created as a result of volcanic eruptions. These areas are made up of basalt, and given that they seemed almost waterlike, the astronomers in the distant past mistook them for seas, whence their name comes.
When it comes to craters, their origin is quite similar - volcanic eruptions created them. When lava starts erupting from a volcano, it has to get out from somewhere - and thus craters are created. If you are referring to lunar craters, however, there are many speculations as to how they were created: due to volcanic eruptions, meteoric impact, or glacier activity.
Here is a picture of the basic life cycle of a plant.
