This is a challenging question, though the initial elimination is straightforward. Position 1 is incorrect because the subsequent sentence beginning with the conjunction 'yet' doesn't properly contrast with the given sentence. Position 2 also fails to justify the contrast with the following sentence. Positions 3 or 4 could be correct, but there needs to be a justification. The given sentence seems more of a conclusion, especially with the phrase 'the internet has proved to both a blessing and a curse,' giving it a concluding tone. Thus, position 4 is the right placement for the sentence. The pronoun 'it' in the penultimate sentence doesn't refer to the noun 'internet' but instead to what has been stated in the sentence before it: '...such readily available knowledge leads many more students away from serious study...''It has let people choose sources that reinforce their opinions rather than encouraging them to question inherited beliefs.'