Manifolds are:

• A. A series of pipes that carry fuel to injectors
• B. The group of valves controlling air intake
• C. A series of pipes and ducts that lead the fuel-air mixture from the carburetor to the cylinders and the exhaust gases away from the cylinders to the main outlet
• D. The engine oil lines

Answer: (C)

Manifolds are the piping networks that route fluids to and from the engine cylinders. In aviation engines, this includes the intake manifold, which distributes the air-fuel mixture from the carburetor or throttle body to each cylinder, and the exhaust manifold, which collects exhaust gases from the cylinders and channels them toward the exhaust outlet. This combined role of delivering the mix to the cylinders and carrying exhaust away defines what a manifold is. The other options describe individual components (fuel lines, valve assemblies) or systems (oil lines) rather than the network that handles both intake and exhaust flows.