这个其实是有3步的 eruptions 是indirect cause; release of methane 是direct cause of the end of the Triassic. 所以第一步是The eruptions of volcanoes,第二步是release of methane,第三步是the end of the Triassic. 但是选项中只考虑了第一步和第二步 所以The eruptions of volcanoes是cause,release of met是effect~