UPSC 2017 CDS II English Paper

‘S’ will be the first part of the given sequence as per the subjectverb agreement rule. PQ will make a pair together as ‘find out what had caused’ makes a logical phrase together. R will come next as ‘food poisoning’ is in the context of ‘caused’ in the previous part. Hence, SPQR is the right sequence. Thus, option (d) is correct.