Final answer:
The Gilded Age refers to a period of economic growth and expansion in the late 19th century. The term 'gilded' highlights the superficial prosperity of the era. The GNP experienced significant growth during this time.
Step-by-step explanation:
The term 'Gilded Age' refers to a period of rapid economic growth and expansion in the United States between Reconstruction and the turn of the century. It was named by Mark Twain, who used the term to criticize the era's greed and corruption. The phrase 'gilded' means that something appears to be golden or prosperous on the surface, but underneath it is not as valuable or perfect as it seems.
During the Gilded Age, the Gross National Product (GNP) of the United States experienced significant growth. The GNP is a measure of the total value of all goods and services produced by a country in a given period of time. While it is difficult to determine the exact percentage of GNP growth during the Gilded Age, it is estimated that the GNP grew at an average annual rate of around 3.8% during this period.