Which of the following results from the fact that signals propagated by the ionosphere are elliptically polarized?

Answer: B. Either vertically or horizontally polarized antennas may be used for transmission or reception

After passing through the ionosphere, signals become elliptically polarized, so their polarization is mixed. That means either vertically or horizontally polarized antennas can be used for sending or receiving. Matching polarization matters far less on these skywave paths.

Tip: On HF skywave, polarization matching is not critical.