Two functions of a cylinder head?

• A. Seals the surface between the cylinder block and cylinder head and seals oil and water passages
• B. Provides mounting for the battery
• C. Houses the exhaust manifold
• D. Sits above the piston to separate the oil from fuel

Answer: (A)

In an engine, the cylinder head serves to close the top end and manage the engine’s fluid passages. It sits on the engine block and, with the head gasket, must create a tight seal to keep compression inside the cylinders and to prevent oil or coolant from leaking into the combustion chamber or between passages. It also contains the internal channels for oil flow to lubricate valve components and for coolant flow to remove heat, so keeping those passages sealed from each other is essential.

That’s why the correct description highlights the two main roles: sealing the surface between the cylinder block and the cylinder head, and sealing the oil and water (coolant) passages. The other options don’t fit because mounting a battery is unrelated to the head, the exhaust manifold is merely attached to the head (not housed by it), and the head doesn’t separate oil from fuel in operation.