What has led to an improvement in lise expectancy

What is the most likely result of specialization in producing products a and b? a) japan stops producing and using product b. b) the u.s. stops producing and using product a. c) the increased output means the u.s. and japan can trade excess units of products a and b. d) specialization means the u.s. will trade 800,000 units of product b for 60,000 units of product a.

Which economic school of thought would explain how massive government expenditures during world war ii sharply move the country out of the great depression

This is for my social studies guide and i can answer 21/22 of it perfectly fine. but can someone tell me what the caste system was, and what divisions/classes that it was apart of it?