How did Leonid Brezhnev demonstrate his use of the Brezhnev Doctrine? O by signing the SALT treaties
O by abandoning the space race
O by curbing military spending
O by sending Soviet troops to Afghanistan

Correct answer is by sending Soviet troops to Afghanistan.

Explanation:

Brezhnev doctrine was focused on the reaction of Soviet troops in the areas where the Socialism was endangered.

That is why the last option is correct as Soviets reacted with military assistance in Afghanistan.

All other options are not correct as they are showing the readiness of Soviet Union to lower the tension in certain period of crisis.

yes

explanation:

the fighting words doctrine, in united states constitutional law, is a limitation to freedom of speech as protected by the first amendment to the united states constitution. in 1942, the u.s. supreme court established the doctrine by a 9–0 decision in chaplinsky v. new hampshire.