[求助]GWD-5-2

According to its proponents, a proposed new style of
aircraft could, by skimming along the top of the atmosphere, fly between most
points on Earth in under two hours.
            

A. According to its proponents, a proposed new style of aircraft
could, by skimming along the top of the atmosphere, fly between most points on
Earth in under two hours.

B. By skimming along the top of the atmosphere,
proponents of a proposed new style of aircraft say it could fly between most
points on Earth in under two hours.

C. A proposed new style of aircraft could fly between
most points on Earth in under two hours, according to its proponents, with it
skimming along the top of the atmosphere.

D. A proposed new style of aircraft, say its proponents,
could fly between most points on Earth in under two hours because of its
skimming along the top of the atmosphere.

E. According to its proponents, skimming along the top of
the atmosphere makes it possible that a proposed new style of aircraft could
fly between most points on Earth in under two hours.

这题的答案是A，我选的D。请NN帮忙作答~~~

在此谢过