A layer of smooth cartilage at their ends, which cushions the bones and prevents them from rubbing directly against one another. The whole joint is also enclosed in a synovial capsule, which is full of synovial fluid. The synovial fluid acts like the oil in an engine, lubricating the joint and preventing the cartilage from becoming worn down.
It is type A because A and B exhibit incomplete dominance
Well assuming the original cell is a prokaryotic, you wouldn't be able to remove the nucleus because prokaryotic cells don't have a nucleus to begin with. if this doesn't help then: The cell would lack genetic information.
A Scientific Hypothesis Must Be "Falsifiable". A scientific hypothesis must be testable, but there is a much stronger requirement that a testable hypothesis must meet before it can really be considered scientific