B or E

@hannahnaylor5, (B) is directly supported by lines 47-54 "the volcanic eruption theory may explain why the end of the Cretaceous period was marked by a gradual change in sea level...several hundred thousand years prior to the relatively sudden disappearances of the dinosaurs, the level of the sea gradually fell.." (E) is the opposite of what the volcanic-eruption theory tells us. LInes 39-47 say that "iridium..would probably be emitted as iridium hexafluoride, a gas that would disperse more uniformly in the atmosphere than the iridium containing matter thrown out from a meteorite impact." Considering a more uniform presence in the atmosphere, iridium would likely to be deposited in clay fairly evenly distributed as well as opposed to "relatively uneven distribution" as (E) suggests. Does this help? Let me know if you have any further questions.