Which of the following best describes the author's tone in this passage

A．while pushing asteroids off course nuclear weapons would destroy the world
B．asteroids racing across the night sky are likely to hit Earth in the near future.
C．the worry about asteroids can be left to future generations since it is unlikely to happen in our lifetime
D．workable solutions still have to be found to prevent a collision of asteroids with Earth

A．They are heavenly bodies different in composition.
B．They are heavenly bodies similar in nature.
C．There are more asteroids than meteoroids.
D．Asteroids are more mysterious than meteoroids.