Amain effect of speculative investment during the 1920s was that it
a. contributed to the stock market crash of 1929.
b. led to great economic growth.
c. resulted in stocks gaining value over time.
d. led to overproduction in the agricultural industry.

A main effect of speculative investment during the 1920s was that it contributed to the stock market crash of 1929.

seeing as no choices were provided, i'll do my best to answer it from knowledge.

job specialization promotes work ethic to the person doing the job. he/she may be strong in the arms and able to lift things, specializing him/her in a job where you lift and carry.