Whenever visible traces of oil are observed on or below the surface of the water in the immediate vicinity of ship or its wake，Governments of Parties to the Convention should，to the extent they are reasonably able to do so，promptly（）the facts bearing on the issue of whether there has been a violation of the provisions of this Regulation or Regulation 10 of this Annex of MARPOL 73/78.

A. observe
B. investigate
C. see
D. look