Music in major keys always gives the impression of happiness and music in minor keys

The type of voice singing this excerpt is

a. alto b. tenor c. bass?baritone

Which does not explain how Miles Davis was able to remain at the forefront of jazz development throughout his career?

a. he hired the best young players to continually challenge him b. he was never content to rely on past successes c. he had an uncanny ability to explore and develop new styles d. he tried to keep up with the styles that were most popular with the public and that record executives wanted most