Robert E. Lee was offered command of Union army after Fort Sumter.
Answer:
1. Observations
2. Hypothesis
3. Experimentation
Explanation:
Observations are made, Hypothesies are formed from observations, and experimnets help alter and comfirm hypothesis.
Well, you don't have the options, but weapons NOT used until WW1 were..
airplanes
balloons
tanks
Hope it helps! :)
Estimates of the population of the world at 10,000 BC have ranged between 1 million and 15 million