What two developments of the 1920s are considered underlying causes of the 1930s depression?

This question is incomplete, here´s the complete question.

What two developments of the 1920s are considered underlying causes of the 1930s depression?

a)  Red Scare and Bonus Army  

b) recession and trade deficit  

c) overproduction and excessive speculation  

d) union strikes and wage-price spiral

c) overproduction and excessive speculation.

Explanation:

Throughout the 1920s, banks engaged in speculation buying, using investors' funds to buy stocks.

When consumer spending started to decline in the spring of 1929, manufacturers faced strong overproduction that led to an excess of goods and a slowdown in production.

However, stock prices kept rising until the stock market reached its peak and then it started crashed. By then, people rushing to withdraw their funds from the banks found they could not be repayed.

in february 1787, congress decided that a convention should be convened to revise the articles of confederation, the nation’s first constitution. in may, 55 delegates came to philadelphia, and the constitutional convention began. debates erupted over representation in congress, over slavery, and over the new executive branch. the debates continued through four hot and muggy months. but eventually the delegates reached compromises, and on september 17, they produced the u.s. constitution, replacing the articles with the governing document that has functioned effectively for more than 200 years.

regarding the law, the 15th amendment was specifically designed thinking in the rights of black free men.

even though ratified on february 3, 1870, the promise of the 15th amendment would not be fully applied for a long time.poll taxes and literacy tests would allow southern states disenfranchise african americans. only in 1965 the voting rights for african americans would be actually able to vote in the south.

in 1965, president johnson signed the voting rights act, which aimed to overcome legal barriers that prevented african americans from voting as it was guaranteed by the 15th amendment to the u.s. constitution.