Answer: B, growing crops during a drought
Step-by-step explanation:
The main challenge of living in a desert is the lack of food, which prompts a need for some way to irrigate crops during a time of water scarcity. Both food and water are critical for humans to survive, so the main priority is to help ensure an ample supply of those two things. Answer B satisfies this.
Although Options A and C is relevant in our modern time, for the people living in the environment plastic doesn't serve as a really helpful or useful case, especially in a survival context. Additionally, while Option C will help, it is not the most relevant detail in terms of survival. Both electric cars and plastics are luxuries.
For Option D, the taste of water is not very relevant to surviving in a desert environment. Humans need water, even if it does taste bad.