Please answer the following question: Write a multi-choice question for the following article, with the given choices and answer: Article: When the earthquake hit Japan on March 11,workers in a supermarket in Japan didn't run away when they felt the shaking. Instead, they held on to the shelves and tried to stop the goods from falling down. Reporters from NHK, the country's largest TV station, stayed calm in front of cameras during the earthquake, even though some were facing real danger. The earthquake was the most powerful one to hit Japan in the country's history. But Japan's reaction to the accident has shown that it is the most earthquake-prepared country in the world. The calm the Japanese showed during and after the quake has impressed the world. This is because Japan has "an earthquake culture".Japanese people are taught how to prepare for and react to earthquakes from a young age. Schools in Japan organize earthquake practices every month. They make students become familiar with being in an earthquake. Japan also has a good earthquake warning system .Warnings were broadcast on television, radio and mobile phones nine seconds after experts first knew about the quake on March 11. The warning system is unable to predict earthquakes. But it can usually _ people about 15 seconds before they feel the effects. Even 15 or 20 seconds can be enough time to save people's lives. Options: A on radio B on the movie C on television D on mobile phones Answer: B on the movie Question:
A:
.After experts first knew about the quake on March 11,warnings were not broadcast _ .