_(blank)_ theory suggests that offenders are rational thinkers and decision makers; however, they choose to participate in disruptive, criminal behavior because they believe their actions will be beneficial.

   Choice Theory

Explanation:  Choice theory says that all behaviour and actions are a matter of choice for reasons that meet one's personal needs. Even these chosen behaviours become central to our existence. These needs are inherent to everyone, but according to this theory, every behaviour, so how we act is a matter of choice. Thus, in this case too, offenders who are rational thinkers have opted for criminal behaviour in an effort to benefit from it, and thus satisfy their existential needs.

  b.

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