General exam question G4A06

WhyAn antenna tuner increases power transfer from the transmitter to the feed line. An antenna tuner matches the transmitter's expected output impedance to whatever impedance the feed line actually presents, so the transmitter can deliver its full power into the line instead of folding back power due to a mismatch, answer C. It does not change the SWR that already exists on the feed line itself between the tuner and the antenna, that mismatch is set by the antenna and feed line and is unaffected by a tuner sitting at the transmitter end, so A (and therefore D, "all of these") is wrong.