Final answer:
Low-frequency sounds maximally distort the basilar membrane at its apical end, which is sensitive to low-frequency vibrations.
Step-by-step explanation:
Low-frequency sounds produce maximal distortion of the basilar membrane at the apical end of the membrane, which is option 2). According to the place theory of pitch perception, different portions of the basilar membrane are sensitive to sounds of different frequencies. High-frequency sounds cause maximal vibration near the base of the cochlea, while low-frequency sounds travel farther along the cochlea and cause maximal vibration at the apex or the tip of the basilar membrane, which is furthest from the stapes.