$3.$ Which characteristic curve is used to represent the relationship between engine load and fuel consumption?

$-$ A$)$ Load Curve

$-$ B$)$ Power Curve

$-$ C$)$ Fuel Consumption Curve

$-$ D$)$ Efficiency Curve

$4.$ What is the effect of increasing the compression ratio on an engine's performance?

$-$ A$)$ It reduces the power output

$-$ B$)$ It increases the thermal efficiency

$-$ C$)$ It decreases the fuel efficiency

$-$ D$)$ It reduces the engine's weight