B. The sum of the protons and neutrons.
D. war was fought on multiple fronts
Answer:
D
Explanation:
WW1 - 1914
Russian Revolution - 1917
WW2 - 1939
Cold War - 1947
Breakup of USSR - 1991
It would be primarily commerce that takes place "within states" that is not a power of Congress, since the main power of Congress in this regard is to regulate interstate commerce.
