The homecare nurse is making a home visit to a 51-year-old female client with a long-standing diagnosis of multiple sclerosis. The nurse knows that the muscle wasting and weakness associated with the disease process are ultimately manifested as a failure of what normal process in muscle tissue?
A. The contraction of fascicles within myofibrils
B. The contraction of the epimysium
C. The surrounding of fascicles by perimysium
D. Thick myosin and thin actin filaments sliding over each other