Final answer:
The sentences in the article underscore the importance of more durable shelters for refugees, as current tents and makeshift shelters do not last long enough for an average refugee's stay in a camp. The correct answers are 'a' for Part A and 'b' for Part B.
Step-by-step explanation:
The sentences from paragraph 3 develop a key concept of the article by introducing the need for shelters to last longer. This is because nearly 3.5 million refugees live in tent accommodations, with millions more in makeshift shelters that are unlikely to last beyond a year. This sets the stage for discussing the longevity and durability challenges that refugee shelters face, which is a central issue of the article.
The sentence that supports this answer is: "Their mission is especially critical because the average refugee stays at a camp for 12 years." (paragraph 4) This sentence highlights the discrepancy between the average duration of stay in refugee camps and the lifespan of the shelters provided, thereby reinforcing the necessity for more durable shelter solutions for refugees.
In summary, the correct answers are a for Part A and b for Part B, forming a cohesive argument for the need for better, longer-lasting shelter solutions for refugees.