Which is generally true for 160- and 80-meter receiving antennas?

On the 160-meter and 80-meter bands, the external atmospheric and man-made noise floor is incredibly high. Because this external noise completely overwhelms the receiver's internal thermal noise, the primary goal of a receiving antenna on these bands is to improve the Signal-to-Noise Ratio (SNR), rather than simply capturing the strongest possible signal. Because the external noise is so dominant, directivity is vastly more important than efficiency. Highly directional receiving antennas, such as Beverage antennas or small magnetic loops, can null out noise from unwanted directions while favoring the desired signal. Even if these antennas or their feedlines are highly inefficient and have significant signal loss, they attenuate both the signal and the noise equally, preserving the improved SNR. This principle explains why the other options are incorrect. Low-loss coaxial cable is largely unnecessary for low-band receiving because feedline losses don't meaningfully degrade the already high noise floor. Additionally, dedicated low-band receiving antennas are frequently installed very close to the ground and absolutely do not need to be a 1/2 wavelength high to achieve excellent directivity.