This is an average difficulty question. Right from the start we can sense that sentence 1 is likely to start the paragraph. It introduces the idea of 'impartiality and objectivity'. Sentences 2,3 and 4 form one unit because they all revolve around Twitter. The algorithm that statement 4 talks about must be about algorithm that twitter would be using. The pronoun "it' in statement 2 refers to Twitter. Thus 2 must come after 3.32 is a pair. The problem of transparency in statement 2 is further elaborated in statement 4 . Statement 2 says that the problem of transparency lies in something...statement 4 takes over by saying ..we are only told some of the basic principles..(the