Option A states that the confidence with which we maintain something to be true is 'usually independent of the source' of the alleged truth. This is the exact opposite of what the passage states in the last few lines: ' And we examine our convictions more or less closely, explain them more or less extensively, and defend them more or less vigorously, usually depending on .... what resources are available for reassuring ourselves or making our beliefs credible to others (look, it's right here on the page; add up the figures yourself; I happen to be a heart specialist).'

Option B states that if we are confident that knowledge is 'widely held', then actions taken on the basis of presumed knowledge become rational and justifiable. This is not what the passage says. The passage states that unless we distinguish knowledge from opinion, wishful thinking or delusion, the actions we take on the basis of presumed knowledge will be irrational and unjustifiable.

Option C sums up the main idea of the second paragraph:'For, the sceptic will note, since reality, under that conception of it, is outside our ken, we have no way to compare our mental representations with things-as-they-are-in-themselves and therefore no way to determine whether they are correct or incorrect.'The author is hence likely to support statement C.

According to the passage, the sceptic questions our ability to know 'reality' defined as things-as-they-are-in-themselves, independent of our perceptions, ideas or descriptions because 'it floats above the processes of our conceiving it'.

Option D states that the sceptic would advocate knowing reality independently. This is incorrect.