Detailed Instructions: In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.
Q: Japan's Chikyu Hakken is trying to reach this region, and n-waves travel along its upper boundary. Post-perovskite forms in the bottommost part of this region, the D double prime layer. P-waves slow down and S-waves disappear past the bottom of this region, and its top features a P-wave velocity jump from approximately seven to approximately eight kilometers per second. The low velocity zone of the asthenosphere is found in the upper part of this region. It is sandwiched between the Gutenburg discontinuity and the Moho, and this layer's namesake plumes form hotspots. For 10 points, name this layer of the earth between the crust and the core.
A:
Science