What components are included in the upper receiver of the rifle?

The upper receiver of a rifle plays a crucial role in its functioning, and understanding its components is vital for maintenance and operation. The correct option includes key components that are integral to the upper receiver's structure and function.

The ejection port is a necessary feature that allows spent casings to exit the rifle after firing. Without it, the rifle would not be able to cycle properly. The housing for the gas key is also included, which is essential for the operation of gas-operated rifles, directing gas from the fired cartridge to cycle the action. Finally, the mounting surfaces for the carrying handle indicate that the upper receiver accommodates various accessories, ensuring that optics and sights can be attached securely to enhance aiming and accuracy.

This explanation illustrates how the components listed in the correct answer directly contribute to the upper receiver's function, encompassing essential features that promote efficient operation of the firearm.