Sienna made a chart listing the steps that describe how a four-stroke heat engine operates.
COM
Step
1
Name
intake
2
ignition
Description
piston moves down and fuel-air mixture
enters cylinder
spark plug fires and causes combustion,
leading to gas expansion
piston moves up and temperature of gas
increases
piston moves up, pushing burned gas
through exhaust valve
3
compression
4
exhaust
Which best describes Sienna's error?
o The descriptions for intake and ignition should be switched with one another.
O During compression, temperature does not increase, it decreases.
O Compression happens before ignition, so it should be step 2.
O The piston moves down, not up, during the exhaust step.