Which of the following represents the FOURTH sentence in the correct arrangement?

A and D make a pair because A talks about 'Russian, Iranian and Young Turk revolutions' and D refers to these upheavals (a violent or sudden change or disruption to something; synonym of revolutions) with the pronoun 'these'. C should immediately precede A because sentence A refers to a singular revolutionary with the pronoun 'he'; and only C talks about a singular revolutionary (Rostom). Also, C should be the first sentence in the correct sequence because it introduces the revolutionary and the overall theme of the paragraph. Thus, the correct sequence should start with CAD. F uses the phrase 'in all three cases' which refer to the idea stated in D (these upheavals) and hence F should be fourth in the correct sequence. E has been placed in its correct position i.e. fifth in the sequence; that leaves B with only one position - the last. Hence the correct sequence should be CADFEB. The correct arrangement is CADFEB; hence sentence F is fourth in the correct arrangement. Answer is option (d).