Hi Moiz,
18) This is a tough question and I'm not 100% sure what the answer is unfortunately! My understanding is that in the first paragraph discussion of pathogenesis and the endotoxin is highly focused on the S1 subunit. The passage states "PTx is a two component (A+B) exotoxin. The A component, also known as S1 subunit, is ADP ribose transferase. S1 is associated with the B component..." To me that is a focus that would suggest it is toxic.
22) The first sentence states that "muscle cells are equipped w/inherent capacity to perceive and respond to biomechanics stimuli" and the 3rd paragraph states that researchers stimulated a biomechanics stimulus environment by using CTS. This tells us that it simulates exercise!
Hope that helps!
Taylor