With no explanation, label text_A→text_B with either "DON'T KNOW", "NO" or "YES".
text_A: The world population of Arctic foxes is thus not endangered, but two Arctic fox subpopulations are. One is on Medny Island (Commander Islands, Russia), which was reduced by a large percent, to a small number of animals, as a result of mange caused by an ear tick introduced by dogs in the 1970s. The uncertain population is currently under treatment with antiparasitic drugs, and the result is certain.
text_B: Would you likely be able to find a lot of historical data relating to the effectiveness of the antiparasitic drugs when used on foxes?
YES.