At a nation's saddest moment, its greatest heroes are born. On September 11th, 2001, many police officers and government officials in America worked day and night to save lives from the big fire at the World Trade Centre. And in Japan, after the serious earthquake, a group of workers showed their courage. The earthquake on March 11th made Fukushima Nuclear Power Plant  turn off and stop its protective cooling systems. And later, a fire broke out.  Workers were told that the plant's radiation  could be harmful to human health. Hundreds of workers left the plant quickly. However, a group of workers decided to fight against the fire and the damage, though they knew it could cause very serious health problems. There were 50 workers in all, so they were also named the "Fukushima 50". The workers worked in shifts . People knew little about the workers, who were mainly experts   with the skills to control the situation. One woman said that her father had volunteered to stay there. "I heard that he volunteered even though he would retire  in just half a year and my eyes were filled with tears. I am really proud of him. And I pray for his safe return. Which of the following is TRUE?
The woman learned something about her father. A woman's father who had retired from work still stayed there. Little was known about the workers when the passage was written. The workers didn't know staying in the nuclear plant was harmful to their health.