31. A star will compress itself into a white dwarf, a neutron star, or a black hole after it passes through a red giant stage, depending on mass. (A) A star will compress itself into a white dwarf, a neutron star, or a black hole after it passes through a red giant stage, depending on mass. (B) After passing through a red giant stage, depending on its mass, a star will compress itself into a white dwarf, a neutron star, or a black hole. (C) After passing through a red giant stage, a star’s mass will determine if it compresses itself into a white dwarf, a neutron star, or a black hole. (D) Mass determines whether a star, after passing through the red giant stage, will compress itself into a white dwarf, a neutron star, or a black hole.（D） (E) The mass of a star, after passing through the red giant stage, will determine whether it compresses itself into a white dwarf, a neutron star, or a black hole. 为什么不选B呢？ | 
