Can you negate answer choice B

@RS1, Negating (B), we have "Exercising the muscles on the opposite sides of the spine unequally DOES NOT TEND to lead to unbalanced muscle development." In looking back at the argument, the intermediate conclusion states that one needs to have balanced muscle development, and this statement goes on to support the overall conclusion that one should exercise both sides of their back equally. This requires assuming that exercising both sides of the back equally helps to develop balanced muscular development in the back. If the argument is assuming that exercising both sides of the back equally leads to balanced muscular development, this requires also assuming that exercising unequally leads to unbalanced muscle development. Thus, negating (B) destroys the argument, so this is why (B) in its original form is a necessary premise. Does this answer your question? Let us know if you have any other questions!