Rheumatoid arthritis is caused by the release of enzymes by a certain organelle into the joints, which then digests the surrounding tissue and causes the subject pain. which organelle is probably the culprit

Lysosomes are the organelles responsible for this behavior.  They contain enzymes that breakdown biological polymers such as proteins, nucleic acids, carbohydrates and lipids. When the enzymes are released to the joints, they digest the tissues and cause pain. Rheumatoid arthritis is an autoimmune disease which means that the immune system responds in opposition to its own healthy cells. 

metamorphism is the change of minerals or geologic texture (distinct arrangement of minerals) in pre-existing rocks (protoliths), without the protolith melting into liquid magma (a solid-state change). the change occurs primarily due to heat, pressure, and the introduction of chemically active fluids. i hoped i !

if your own plato the answer is b. the fern transitioned from sporophyte generation to gametophyte generation.