During the 1920s, the prevailing attitude about the economy is best described as

During the 1920s, the prevailing attitude about the economy is best described as optimistic.

People became careless about their spending in 1920s and spent a lot more money on themselves. this lead to a booming economy but that was very short-lived and ended with the great depression beginning in October of 1929. the 1920s also had growing gap between the poor and rich if that's relevant to your question.  

C. it's a true fact. i know because we are studying about the great depression. so it best illustrates a claim of fact. thx. have a wonderful day!