Which major component group of the M9 service pistol houses the firing pin and extractor?

The major component group of the M9 service pistol that houses the firing pin and extractor is the slide assembly. This assembly is crucial to the pistol's operation as it contains key components involved in the firing process. The firing pin, which strikes the primer of the cartridge to initiate firing, and the extractor, which removes the spent cartridge casing from the chamber after firing, are both located within the slide.

Additionally, the slide assembly contains other vital elements, such as the recoil spring and the breech face, which also plays significant roles in the pistol's cycle of operation. In contrast, the receiver assembly is generally responsible for providing the framework that houses the trigger, hammer, and other internal mechanisms but does not contain the firing pin and extractor. The frame assembly serves primarily as the grip and structure for holding the other components in place, while the barrel assembly is focused on guiding the bullet as it exits the pistol. Thus, the slide assembly is the correct choice because it specifically contains the firing pin and extractor, essential for the firearm’s functionality.