B. problems could be solved using human reason.
The Enlightenment was an 18th century philosophical movement. One of their favorite words was 'reason.'
C. Native American communities occupied vast acres of desirable land.
Andrew Jackson's Indian removal policy in 1838 and 1839
Technology of warfare changed drastically during the first world war with the introduction of new weaponry and machinery.
Explanation:
These were some of the most important innovations of the time.
Flamethrower
: This was one of the most inhumane weapon that was brutally effective in closed quarters but could also kill people in friendly fire.
Machine gun
: The introduction of machine gun made firing to enemy lines much easy.
Gas shell
: These were a potent weapon of the time and were shorty discontinued.
Submarine
: The first submarines were introduced in the end of world war but were not very useful.
Tank the tank was also a modern introduction in the end of world war.
Trench system was the way of warfare that completely campaigned the pitched battle into a long drawn conflict with small gains and losses.