Some Marine Corps squadrons to fly the FA-35 C carrier base Lightening ll aircraft. That make sense since the F-35 B's don't have a tailhook and can't operate from aircraft carriers. I was never able to figure out why the Marines went with the F-35 B except that they could operate from amphibious assault ships like the LHD and LHA's. making these ships small aircraft carriers. U.S. Navy Carrier Air Wings always had one Marine fighter squadron attached to the CAW operating from USN aircraft carriers after the Clinton administration and the Democrats in Congress over downsized the U.S. Navy. F-35 C
That is exactly why they adopted the B. Basically it was needed to replace the antiquated AV8B HARRIER series. A good CAS bird for it's era, that era was the 1970's and early 1980's. By the 2000's, that day was past and it was being challenged in fulfilling it's 2 roles (maintaining a CAP over deployed amphibious assets, and providing CAS to those assets). A new aircraft was needed, and eventually that became a key feature of the F35 program.