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 some 85–90%, to around 90 animals, as a result of mange caused by an ear tick introduced by dogs in the 1970s. The population is currently under treatment with antiparasitic drugs, but the result is still yet to be seen.
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?
NO.