Question

During the stage of internal combustion engine operation in which the piston rises and compresses the fuel in the combustion chamber,

a. both the intake and exhaust valves are closed.
b. both the intake and exhaust valves are open.
c. the exhaust valve is open and the intake valve is closed.
d. the intake valve is open and the exhaust valve is closed.

Answer 1

your answer is a. both the intake and exhaust valves are closed.

i just took the test

Answer 2

The piston rises and compresses the fuel in the cylinder during
the "compression" stroke.

Both valves have to closed in order to compress the fuel in there.

If either valve were open, just a crack, then the gases wouldn't get
as compressed as they should ... they'd just get forced out into the
fuel line or the exhaust line through the open valve.