It would be best to include research and studies done by .gov sites (government sites) such as the USDA and FDA. One other source that can be reliable is a .edu site used by a college that has does research on the topic.
It depends of the country and the population of the region, but i'd say 10 years, so ''a.''
This Act provided for unemployment insurance, old-age insurance, and means-tested welfare programs. The Great Depression was clearly a catalyst for the Social Security Act of 1935, and some of its provisions—notably the means-tested programs—were intended to offer immediate relief to families.