The paragraph discusses how rats have managed to survive all efforts to destroy them through various means of poisoning, trapping, fumigating, flooding, burning, and even surviving atomic bomb tests. Despite all attempts to eliminate rats, they continue to prove themselves as extremely resilient and indestructible pests. The topic sentence introduces how rats have survived extermination attempts, and the rest of the paragraph provides supporting details on the many strategies used against rats and how they continue to evade such efforts.