The Following Questions Refer to the Graph Below $\quad$ -The Growth of Corporations

The following questions refer to the graph below.
Index of Common Stock Prices (1926=100)

-Using your knowledge of United States History,answer parts a,b,and c.
a)Briefly explain why ONE of the following most significantly changed the nature of the United States' economy.
$\quad$ -The growth of corporations
$\quad$ -American expansion overseas
$\quad$ -The New Deal
b)Provide ONE piece of specific historical evidence to support your explanation.
c)Briefly explain why ONE of the other options is not as good as the one you chose.