Q: Read the following article and answer the question. Article: Rock and roll music developed in the United States in the early nineteen-fifties. It was based on the music called rhythm and blues that was performed by African American musicians. Early rock and roll singers developed their own kinds of music. Elvis Presley, Chuck Berry, the Beach Boys, and Bob Dylan were the most popular rock and roll musicians in the early 1960's. All were American. Then, in 1964, a new rock and roll group from England invaded America: the Beatles. Some people say the Beatles' music shook America like an earthquake. The Beatles changed rock and roll forever. Their early songs were influenced by American rock and roll musicians, including Chuck Berry. But the Beatles looked different and sounded different from any musical group before them. The Beatles released their first album in the United States in 1964, when all of the top five records in America were by the Beatles. In 1967, they released an album called "Sergeant Pepper's Lonely Hearts Club Band." It was one of the first "concept" albums. That is, all the songs were linked by a common story or idea. The popularity of the Beatles led the way for more rock and roll bands from England to become popular in America. The Rolling Stones was the most important of these bands. The Rolling Stones is one of the few groups from the 1960's that is still performing and recording today. In 1965, the group recorded one of its most famous songs, "Satisfaction". The musical instrument most linked to rock and roll is the guitar. Experts say Jimi Hendrix was one of the most influential guitar players in rock and roll during the late 1960's. His "Purple Haze" was liked by many people. By the 1970's, rock and roll music became known as rock music. It expanded into many new forms. For example, there was country rock, hard rock, acid rock, and heavy metal rock. Punk rock, jazz rock, and glitter rock. In the middle 1970's, experts say rock music regained some of the energy of early rock and roll. Bruce Springsteen and the E Street Band became popular with... Question: The main topic of this passage is _ . Answer:
The answer is:
the development of rock and roll music