A is a meeting of party members in which nominees are selected informally. The process relies on voting methods such as dropping marbles in a jar, placing names in a hat, standing under a sign bearing the candidate’s name, or taking a voice vote.

Caucus

Explanation:

A caucus is a meeting of a political party or organization, that is informal, not very structured, and that can include a few people to up to thousands.

Caucusus originated in colonial North America, and the origin of the term, while unclear, traces back to that era.

In a caucus, instead of voting by ballot, attendees vote by the methods explained in the question: dropping marbles in a jar, or placing names in hat, or simply standing, or raising the hand.

Perhaps the most famous caucus is the Iowa caucus, which is the first state electoral primary during the U.S. presidential election.