According to the passage, the decisive factor in maintaining a firm’s competitive advantage is______.

A．Because they are well made and the stories are interesting.
B．Because the heroes have to cope with many problems and frustrations.
C．Because the characters in the movies are free go do whatever they like.
D．Because good guys in the movies always win in the end.

A．The local Africans are peace-loving people.
B．Soda bottles are very precious in some remote areas.
C．A trivial thing may sometimes bring about undesirable consequences.
D．Caution must be taken in introducing new technology.