Final answer:
Elvis Presley and Chuck Berry contributed to the development of rock by affirming its core values and exploring a wide range of influences.
Step-by-step explanation:
The two musicians or groups that contributed to the development of rock by both affirming its core values and exploring a wide range of influences are Elvis Presley and Chuck Berry. Elvis Presley, a teen heartthrob, rose to stardom by merging country music and rhythm and blues into a new genre known as rock 'n' roll. Chuck Berry, on the other hand, combined rhythm and blues with rock and roll, dazzling audiences with his guitar solos and electrifying performances.