Vocabulary in Context — Prelims Questions

In the passage: 'The government's new policy proved to be quite efficacious in addressing the unemployment crisis, unlike previous measures that had been largely ineffective.' What does 'efficacious' most likely mean in this context?

From the passage: 'The scientist's perspicacious observations led to breakthrough discoveries that had eluded researchers for decades.' In this context, 'perspicacious' most nearly means:

In the sentence: 'The new environmental regulations will help ameliorate the pollution problem that has plagued the city for years.' What does 'ameliorate' mean in this context?

From the passage: 'The CEO's decision to divest the company's non-core assets was seen as a strategic move to focus on primary business operations.' What does 'divest' most likely mean?

In the passage: 'The ancient manuscript's text was so archaic that even scholars found it difficult to decipher without extensive linguistic analysis.' What does 'archaic' mean in this context?