A composition of copper and silver is identified as which?

The correct identification of a composition of copper and silver is an alloy. An alloy is defined as a mixture of two or more elements, where at least one of the elements is a metal. In this case, copper and silver together form a metallic composite, which fits the definition of an alloy.

Pewter is primarily composed of tin, with varying amounts of other metals like lead, copper, or antimony, and does not typically include silver as a primary component. Brass is an alloy of copper and zinc, not silver. Bronze is primarily an alloy of copper and tin, which also does not involve silver. Therefore, the best and most accurate classification for a mixture of copper and silver is an alloy.