Answer: Im pretty sure its one, three and four
Explanation: I toke Geography
<span>During the stage of internal combustion engine operation in which the piston rises and compresses the fuel in the combustion chamber, the intake and exhaust valves will both be closed. This means that the mixture of fuel and air are compressed, due to the seal around the combustion chamber that has been created by the closure of both of these valves. Hopefully that answered your question for you!</span>
Many things caused the crash. Taxes were too high, bad bank practices caused a recession, and too many workers went on strike (there were many other causes but thats all o could think of)
