What is a primary? who holds the first one?

Primary,  are  chief importance; principal.  "the government's primary aim is to see significant reductions in unemployment" who hold  it is the first binding event, in which a candidate can secure convention delegates, is traditionally the Iowa caucus, usually held in late January or early February of the presidential election year.  that what I read online somewhere.

what are the options

Step-by-step explanation: