Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the best option for each of the blanks.

  The Eighth Wonder of the World The Thames Barrier is a major part of the flood defense scheme for protecting London (35) ______ rising water levels. The defenses (36) ______ include raised river embankments and additional flood gates at strategic points, including the Barking Barrier. The unique structure that is the Barrier spans the 520- metre wide Woolwich reach and (37) ______ of 10 separate movable gates, each pivoting and supported between concrete structures which house the operating machinery. When raised, the four main gates (38) ______ stands as high as a five-storey building and as wide as the opening of Tower Bridge. Each (39) ______ 3700 tones. During the first twelve years of operation the Barrier has been closed twenty nine times to protect London.  

The Eighth Wonder of the World The Thames Barrier is a major part of the flood defense scheme for protecting London (35) ______ rising water levels.