The national geographic findings on the sinking of the maine were mostly based on

 It was based on computer modeling.  However the results were inconclusive. Some believe that it could have been set off by coals from within the ship. There is a suggestion based on the soil depression found in the ship that a small mine could have been detonated.

The National Geographic findings on the sinking of the main were mostly based on advanced computer modeling. The advanced computer modeling refers to a technique that has represented a crucial shift on the creation of art and consists on constructing and manipulating abstract representations of an object simulated  with computer system.  

hello there the answer is a

sorry if i am wrong hope that : )

d) iowa i believe is the answer