From this passage, we can clearly know Japan s warplane……

The newspaper China Daily (1999) reported that fifty-eight years ago, Japan"s warplanes surprised US troops at Pearl Harbor, making the start of Japan"s war against the United States. Last month, however, the Japanese Foreign Minister officially apologized for the first time for not delivering a war declaration beforehand.
It was said that Japan did plan to deliver war declaration before its attack on Pearl Harbor but the declaration was delayed by Japan"s embassy in Washington.
According to the Japanese Foreign Minister, the Japanese government then sent a secret telegram to its ambassador in Washington, asking him to inform US 25 minutes before Japan"s attack on Pearl Harbor, that Japan would stop its talk with America. Not realizing the stop of the talk actually meant a war declaration, the Japanese ambassador didn"t inform US of the Japanese government"s decision in time, thus making a so-called "great historic mistake".From this passage, we can clearly know Japan"s warplanes surprised US troops at Pearl Harbor ______.

A．in 1942
B．in 1940
C．in 1943
D．in 1941