What international treaty, ratified in 2009 by all countries, confronted the issue of ozone depletion?

most people now work in jobs where they do one  kind  of work; they are carpenters, bankers, cooks, mechanics, and so forth. likewise, most  businesses produce  only certainkinds  of  goods  or  services, such as cars, tacos, or gardening  services. this feature of  production  is known as specialization.

number 4. should be the correct answer