Final answer:
The band known as the "American counterpart" to Led Zeppelin in the 1970s is Aerosmith. They were compared due to their similar styles of bluesy hard rock and their energetic performances. Alan Freed was the disc jockey who popularized rock and roll.
Step-by-step explanation:
The band that was seen as the "American counterpart" to Led Zeppelin in the early 1970s is C) Aerosmith. Aerosmith, formed in Boston in 1970, was often compared to Led Zeppelin due to their bluesy hard rock sound and high-energy performances. Frontman Steven Tyler's powerful vocals alongside Joe Perry's guitar riffs drew many parallels to the iconic sound of Led Zeppelin. Although both bands have their unique styles, Aerosmith's rise during the same era often pegged them as America's version of Led Zeppelin, who were quintessentially British.
Regarding the popularization of rock and roll, C) Alan Freed is the disc jockey credited with helping to popularize the genre. Freed notably used the term rock and roll on mainstream radio and organized some of the first rock and roll concerts, contributing significantly to the spread of the genre's popularity.