The phrase "passed over" in Paragraph 3 is closest in meaning to"______".

A．American colleges and universities are a special property of NASA
B．Fresh members from the academic world participate in the program.
C．The program brings new outlooks to NASA space programs.
D．It is important for the space scientists to exchange information and perspectives.

A．Because previous seals all failed.
B．Because it was very complex in running the space program.
C．Because cracks in the seals could be disastrous.
D．Because great care has to be taken of the hydraulic fuel pump sealing.