The use of submarines made attacking or torpedoing ships easily, that made attacking more effective and reduced the chance of home soldiers getting killed.
The emancipation proclamation of 1862 freed slaves in the south
Historical documents revealed American children worked in large numbers in mines, glass factories, textiles, agriculture, canneries, home industries, and as newsboys, messengers, bootblacks, and peddlers.And by 1900, their efforts had resulted in state and local legislation designed to prevent extreme child labor.
Srry i'm soo late but the answer is A. President McKinley's desire for war.
Hope i Helped :)
