Questions: What style of music consists of two or more lines of melody coming together to create one harmonic texture?

The answer is polyphony.

Viols are a family of string instruments used primarily during the Renaissance and Baroque periods. They are not a style of music but rather instruments that can be used to perform various musical styles.

Monophony refers to a musical texture consisting of a single melodic line without any harmonic accompaniment. It is the simplest form of musical texture, exemplified by plainchant or Gregorian chant.

Polyphony is a style of music where two or more independent melodic lines are played or sung simultaneously, creating a complex and harmonious texture. This style was prominent during the Renaissance and Baroque periods and is exemplified by the works of composers like Johann Sebastian Bach.