As the Baby Boomer Generation Ages, More and More Joint

As the Baby Boomer generation ages, more and more joint replacement surgeries take place each year. Hip replacement surgery is the gold standard of all joint replacement surgeries, with many patients able to walk just a few hours after surgery and return home the very next day. In contrast, knee replacement surgery usually requires hospital stays of several days, followed by weeks to months of physical therapy. What best explains why the recovery after hip replacement surgery is so much faster than after knee replacement surgery?

A) The knee is a type of combination joint, which are difficult to replace.
B) The upper end of the thigh bone has less overall surface contact with the hip bone than its lower end has in the knee with bones of the lower leg.
C) The knee joint is stabilized by many more structures (many of which have to be cut) than the hip joint.
D) The hip joint is more superficial and more accessible to surgeons than the knee joint.
E) The hip only moves in one direction, and recovery of one motion is easier than recovering movement in many directions.