ANS:C - both (a) & (b)

A spark ignition petrol engine typically has both a throttle valve and a carburetor. The throttle valve, also known as a throttle plate or throttle body, controls the amount of air entering the engine. It is positioned in the air intake system and is operated by the driver through the accelerator pedal. By adjusting the opening of the throttle valve, the engine's power output can be regulated. The carburetor is a device that mixes air and fuel in the correct proportion for combustion in the engine cylinders. It is typically located between the air filter and the intake manifold. The carburetor regulates the flow of air and fuel into the engine based on the engine's operating conditions. So, the correct answer is: both (a) & (b)