answer: #Person2# wants #Person1# to have the check certified because it's their policy.
documents: #Person1#: Could you tell me which kind of payment you'll choose?
  #Person2#: We're going to pay by check.
  #Person1#: Will you please have the check certified?
  #Person2#: If you think it is necessary.
  #Person1#: It's just our policy. We would accept a certified check or a direct bank remittance.
  #Person2#: OK, no problem.