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, and the result is certain.
text_B: Would a scientist working with the Arctic foxes on Medny Island be able to give you an accurate estimate of how many are alive today?
YES.