Answer:
A. Participating in a caucus takes longer than voting in a primary, so
voter participation in caucuses is lower.
Step-by-step explanation:
Caucuses are reunions and votations were the affairs of political parties are decided, from presidential race candidates to logal representatives and local party leaders, caucuses as well as primaries are only for registered party members and it can take days of discussions and decisions, this factors are mainly why they have a significantly lower bote turnout than the primaries, since in primaries party members just show up and vote.