As a result of the battles of Trenton and Princeton during the American Revolution?

Battles of Trenton and Princeton, (1776–77), in the American Revolution, a series of engagements won by the Continental Army against Hessian and British forces in New Jersey. The victories restored American morale and renewed confidence in Washington

in the 1950s, country music came into its own before rock-n-roll took off in the 60s while jazz and classical music continued to innovate

d is the right answer