In Several States, Notably Among Them Iowa and Nevada, the Presidential

In several states, notably among them Iowa and Nevada, the presidential nominating process begins with party caucuses, which are:

A) a series of closed, regional primaries, with run-off votes.
B) a series of regional conventions, which precede state conventions.
C) synonymous with state party conventions.
D) local party meetings that involve extensive discussions among registered party voters who attend, and which involve delegate selection.