[单选题]‡ 年 2 月 23 日,公安部党委副书记、常务副部长王小洪在《人民日报》发表一篇题为《全力推动新时代公安工作高质量发展》署名文章。文章指出,公安机关要始终坚持最高政治原则和根本政治规矩。最高政治原则和根本政治规矩是:
A.万无一失、一失万无
B.“两个维护”
C.绝对忠诚、绝对纯洁、绝对可靠
D.政治安全、人民安全、国家利益至上有机统一

Space is a dangerous place, not only because of meteors(流星)but also because of rays from the sun and other stars. The atmosphere again acts as our protective blanket on earth. Light gets through, and this is essential for plants to make the food which we eat. Heat, too, makes our environment endurable. Various kinds of rays come through the air from outer space, but enormous quantities of radiation(辐射) from the sun are screened off. As soon as men leave the atmosphere they are exposed to this radiation but their spacesuits or the walls of their spacecraft, if they are inside, do prevent a lot of radiation damage.
Radiation is die greatest known danger to explorers in space. The unit of radiation is called" rem". Scientists have reason to think that a man can put up with far more radiation than 0.1 rem without being damaged; the figure of 60 rems has been agreed on. The trouble is that it is extremely difficult to be sure about radiation damage--a person may feel
A. the Apollo mission was very successful
B. protection from space radiation is not a easy job
C. astronauts will have deformed children or grandchildren
D. radiation is not a threat to well-protected space explorers