Scientific knowledge has its dangers but so has every great thing. Over and beyond the dangers with which it threatens the present, it opens up as nothing else can, the vision of a possible happy world; a world without poverty, without war, with little illness. Science, whatever unpleasant consequences it may have by the way, is in its very nature a liberator.

Correct Option (A)

The passage acknowledges the inherent dangers associated with scientific knowledge. However, it predominantly emphasizes science's unique capacity to envision a future free from poverty, war, and widespread illness. This 'possible happy world' is presented as a vision or a potential outcome that science can unlock, rather than a guaranteed certainty. Therefore, a happy world is depicted as a dream or an aspirational goal facilitated by scientific advancement.

Incorrect Options:

• Option (B) states that science is the only major threat. While the passage mentions the dangers of scientific knowledge, it does not assert that science constitutes the sole or primary threat to a happy world. It merely acknowledges that, like any great endeavor, science carries risks.
• Option (C) claims that a happy world is not possible without science. The passage highlights science's significant potential to contribute to a happy world and describes it as a 'liberator'. However, it does not explicitly state that science is the exclusive prerequisite for achieving such a state, implying other factors might also contribute.
• Option (D) suggests that a happy world is not at all possible with or without science. This contradicts the central theme of the passage, which explicitly states that science "opens up... the vision of a possible happy world" and is "in its very nature a liberator." The passage clearly indicates science's potential to facilitate a better world.