Solution:The given sentence starts with Part B as it introduces the main subject of the sentence i.e. Data on vulnerable population. And, Part A states additional information about the subject.
So, A will follow B. Further, Part C states another clause connected with conjunction 'and' & Part E has a gerund phrase that explains the reason why collecting data is crucial.
So, E will follow C. At last, Part D states another clause connected with the conjunction 'and'. Going through the options, option (c) has the correct sequence.