Which of the following is true of Livingston？ ______

A. He thinks he has discovered a new possibility in the link between sun spots and the weather on the Earth.
B. He has great doubts about the theory that the sun's frequent changes have an influence on the Earth's climate.
C. He has been recently informed by other scientists of the possibility that more sun spots will appear.
D. He does not think the causes of the sun spots will be fully revealed by scientists in the near future.