During the swing era, economically speaking, American labor industries increasingly turned to and to make the economy run more efficiently.

machines; new technologies

Explanation: A number of factors all coalesced into the great depression of 1929. This was a time followed by the swing era (1933 - 1947)— the period of time when big band swing music was the most popular music in the US. However, there were a variety of economic changes in great depression that helped Americans cope with the undue hardship caused by the depression and the war that followed. At this time of slow growth, American labor industries increasingly turned to machines and new technologies to enable the economy run more efficiently which helped saved time in producing goods or delivery of services, contributing to the overall profits of the American businesses. It also contributed to the efficiency of a business's output rate, allowing for larger quantities of products to be moved or of services to be rendered.

b. a single paragraph.

a paragraph is a series of sentences that are organized and make sense, and are all related to a single topic . almost every piece of writing you do that is longer than a few sentences should be organized into paragraphs. this is because paragraphs show a reader where the subdivisions of an essay begin and end, and thus the reader see the organization of the essay into subjects in order to be able to understand its main points.