According to Carl Perkins, a country take on rhythm and blues, performed mainly by white Southerners, that combined elements of country music with rock and roll. This style was most popular in the mid fifties.

A. A second melody playing under the main melody.

B. A regional style of rock from California notable for high-register close harmony vocals and innovative guitar effects.

C. The process of recording each part of a performance separately, then mixing them into a complete performance.

D. The Beatles, along with their producer George Martin, were among the first to take full advantage of this technique.

According to Carl Perkins, a country take on rhythm and blues, performed mainly by white Southerners, that combined elements of country music with rock and roll. This style was most popular in the mid fifties.

B. A regional style of rock from California notable for high-register close harmony vocals and innovative guitar effects.

Explanation:

The answer a is incorrect because a second melody playing under the main melody is known as polyphony. The answer c is incorrect as the process of recording each part of performance separately, then mixing into a complete performance. This is known as multi-track recording. The answer d is incorrect as the Beatles, along with their producer George Martin, were not among the first to take full advantage of this technique as in UK the the first ones were Teddy Boys.