Supply is how much there is of a product. Demand is how much the product is wanted or needed by consumers. When supply is low, & demand for the product is high, it forces the price to go up.
The weapon that helped continue the stalemate on battlefields during World War I is option<em> D. Machine Gun</em>. A stalemate is a situation in which neither side has a clear victory over the other. The war becomes very long and slow, and armies have to be creative to surprise the enemy. There were many stalemates in WWI, especially in the Western Front.
Basically it's a key to candidates because it is considered to influence the overall result of the president election. Democratic and Republicans both have a good chance to gain a win.
Assuming the t or f stands for true or false, the answer would almost definitely be True.<span />