Final answer:
The ad agency that hired its first full-time copywriter in 1892 is N.W. Ayer & Son. They played a significant role in shaping the advertising industry during the late 19th and early 20th centuries.
Step-by-step explanation:
The ad agency that hired its first full-time copywriter in 1892 is N.W. Ayer & Son. N.W. Ayer & Son is widely considered to be the first full-service advertising agency in the United States, establishing many of the practices and strategies that are still used in advertising today. One of their notable early campaigns was for the Pears Soap company, where they created the famous slogan 'Good morning, have you used Pears' soap?' to promote the product. N.W. Ayer & Son played a significant role in shaping the advertising industry during the late 19th and early 20th centuries.