Help me I need help with this I don’t know what answers

What event had weakened florida’s economy immediately before the start of the great depression? a) the freezing of orange trees b) the end of florida’s land boom c) the start of another world war d) the building of florida’s railroads

Which statement best evaluates the impact of the 1929 stock market crash on europe? 1. the united states established high export tariffs to europe that reduced goods exported to germany. 2. the united states promoted domestic policy initiates that reduced jobs on american bases in europe. 3. the united states promoted isolationism that withdrew troops from europe causing germany to pay its own national defense. 4. the united states eliminated loans to europe that caused germany to default on its reparation payments to france.

Why are primary sources important when studying historical events