Before blank space a question is posed. And after the blank space reasons which can be associated with poor people themselves is discussed so the blank space should have a special mention of poor people whether in form of question or a simple statement (b) & (d) won't fit well here so they can be ruled out. Rich is not even introduced in passage till this point, therefore option (e) can also be rejected. Additionally Option (a) gives a logical and sensible flow to the passage.