Which action is restricted to members of a political party?

Voting in a closed primary

A closed primary is a type of direct primary limited to registered party members, who must affirm their party affiliation in order to vote. The closed primary serves to encourage party unity and prevent members of other parties from subverting a party by nominating weak candidates..

it refers to race, i am pretty sure this was a popular term in nazi germany or something.

in 1859, brown and 21 of his followers attacked and occupied the federal arsenal in harper's ferry. their goal was to capture supplies and use them to arm a slave rebellion. brown was captured during the raid and later hanged, but not before becoming an anti-slavery icon. abolitionist and insurrectionist

explanation: