Which of the following types of propagation is most commonly associated with occasional strong signals on the 10-, 6-, and 2-meter bands from beyond the radio horizon?

Answer: B. Sporadic E

Sporadic E brings occasional strong signals from beyond the radio horizon on 10, 6, and 2 meters. It comes from patches of dense ionization in the E region that appear without much warning.

Tip: 6 meters is called the "magic band" partly because of sporadic E.