Extra exam question E1A04

WhyAn Extra class operator may not answer a CQ on 3.601 MHz LSB phone because the signal's sidebands extend down past 3.600 MHz into the segment reserved for CW and data. The 80-meter phone segment that Extra class operators may use begins at 3.600 MHz. An LSB signal's sidebands extend downward from the displayed carrier frequency, so a station at 3.601 MHz with a normal phone bandwidth has sideband energy reaching down past 3.600 MHz into the segment below, which is restricted to CW and data emissions, answer C. The carrier frequency alone being inside the phone segment isn't enough, what matters is where the actual occupied bandwidth falls, and 3.610 MHz isn't a real US phone-band boundary.