Aregion distinguished by uniformity of one or more characteristics that can serve as the basis for an areal generalization and of contrast with adjacent areas.

I believe the answer is: Formal region

Each formal region would be differentiated by their own unique government structure that separate each region with the other. Each border on the sides of each region would consist of some sort of boundaries ( could be natural or human made) that accepted by all regions as a legal separation between their jurisdiction.

giant impact theory - the moon was formed from the collision between earth and another mars-sized body.

colliding planetesimals hypothesis - the moon was formed from the same cloud of material as earth.

capture hypothesis - the moon was locked into orbit by earths gravity as it was passing by it.

accretion hypothesis - the moon was formed from collisions and combining of planetesimals.

i think this is right, if not and you know better let me know.

  b.

there are isolated pockets of farming, generally around rivers and oases, which are used for irrigation.