Athe simplest and most familiar form of is a work in which each voice enters in succession with the same melody that can be repeated endlessly.

The correct answers are: 1- Round 2- Composition.

Explanation:

A round can be understood as a musical composition in which the voices of a certain piece enter succesively and they proceed to sing the same melody. There's no particular time or place where the voices need to stop singing the melody so they may repeat it endlessly.

The rule of a round is that the voices enters at the same pitch while using the same notes so it sounds harmoniously.

So in conclusion, a Round is the simplest and most famliar form of musical composition/ canon, is a work in which each voice enters in succession with the same melody that can be repeated endlessly.