Identify a restriction in the passage of a carburetor that causes air to move faster?

The correct choice focuses on the Venturi, which is a key component of a carburetor that plays a crucial role in the operation of air and fuel mixture. The Venturi effect refers to the decrease in fluid pressure that results when a fluid flows through a constricted section of pipe. In the case of a carburetor, the Venturi is designed to narrow at one point, causing the air to accelerate as it passes through this restricted space.

As air moves through the narrowed section of the Venturi, its speed increases while its pressure decreases, creating a vacuum that draws fuel into the airstream. This process is essential for mixing fuel and air in the correct ratio for optimal combustion in internal combustion engines. The design of the Venturi is critical because it is this specific constriction that allows for an increase in air velocity, which is necessary for the proper functioning of the carburetor.