Not supported and too narrow. It’s not supported, because the author says only that under certain conditions, drilling will lead to groundwater contamination. But if safeguards are used, we don’t know that contamination is inevitable. (A) is also too narrow, because the contamination of groundwater is merely one example of a problem that can result from drilling. But the author’s point is broader than simply describing one problem of oil drilling.

Too narrow. Although the author does note at the end of the passage what (B) claims, this overall point of the passage isn’t about international concern. The rest of the passage focuses on the insufficiency of regulations to solve the environmental problems caused by oil well drilling.

Too narrow and unsupported. (C) is too narrow because the author’s point isn’t merely that regulations are based on hindsight; it’s that these regulations don’t adequately protect us from the harms of oil well drilling because regulations are based on hindsight. (C) is also unsupported because there’s no suggestion the author thinks hindsight is potentially “reliable” as a means of devising adequate safeguards. The author suggests these safeguards are not adequate.

This best captures the author’s main point. The author discusses the problem posed by the fact that scientific knowledge about environmental impacts of oil well drilling lags behind the actual drilling of oil wells. Although regulations might seem to be a potential solution, the author asserts that these don’t solve the problem, because they’re often based on hindsight or insufficient knowledge.

Too narrow. This is mentioned in P2, but it’s merely offered as an example of how regulations on oil well drilling can be insufficient to protect us from environmental harm.