单项选择题

Thomas Alva Edison was awarded more patents on inventions than any of other American. When he died in 1931, Americans wondered how they could best show their respect for him.
One suggestion was that the nation observe a minute or two of total blackout. All electric power would be shut off in homes, streets, and factories.
Perhaps this suggested plan made Americans realize fully what Edison and his inventions meant to them. Electric power was too important to the country. Shutting it off for even a short time would have led to complete confusion. A blackout was out of the question.
On the day of Edison’s funeral, many people silently dimmed their lights. In this way they honored the man who had done more than anyone else to put the great force of electricity at his countrymen’s fingertips. What does the underlined "blackout" mean in this passage

A.A period of darkness caused by an electrical power failure.
B.A temporary loss of consciousness, sight or memory.
C.A covering for windows that stops light being seen from outside, or light outside from coming into a room.
D.A situation when the government or the public will not allow any news or information on a particular subject to be given to the public.