The underlined structure in the excerpt “the reasons behi

A Incomplete – people still do not know for sure what caused the instability. B Complete – archeologists concluded it was caused by the overweigh. C About to be completed – scientists are close to an exact answer. D Incomplete and will never be completed – specialists do not think they will find an answer. 
E Recently completed – it was possible to investigate when the ship was taken out of the sea.