Khmer Rouge Tuol Svay Pray High School sits on a dusty road on the outskirts of Phnom Penh, Cambodia. In 1976, the Khmer Rouge renamed the high school S-21 and turned it into a torture, interrogation and execution center. Of the 14,000 people known to have entered, only seven survived. Not only did the Khmer Rouge carefully transcribe the prisoners' interrogations; they also carefully photographed the vast majority of the inmates and created an astonishing photographic archive. Each of the almost 6,000 S-21 portraits that have been recovered tells a story shock, resignation, confusion, defiance and horror. Although the most gruesome images to come out of Cambodia were those of the mass graves, the most haunting were the portraits taken by the Khmer Rouge at S-21. Today, S-21 Prison is known as the Tuol Sleng Museum of Genocide. Inside the gates, it looks like any high school; five buildings face a grass courtyard with pull-up bars, green lawns and lawn-bowling pitches. The ground-floor classrooms in one building have been left to appear as they were in 1977. The spartan interrogation rooms are furnished with only a school desk-and-chair set that faces a steel bed frame with shackles at each end. On the far wall are the grisly photographs of bloated, decomposing bodies chained to bed frames with pools of wet blood underneath. These were the sights that greeted the two Vietnamese photojournalists who first discovered S-21 in January of 1979. In another building the walls are papered with thousands of S-21 portraits. At first glance, the photograph of a shirtless young man appears typical of the prison photos. Closer inspection reveals that the number tag on his chest has been safety pinned to his pectoral muscle. With a bruised face and a pad-locked chain around his neck, a boy stands with his arms at his sides and looks straight into the camera. A mother with her baby in her arms stares into the camera with a look of indignant resignation. The photographs and confessions were collected in order to prove to the Khmer Rouge leaders that their orders had been carried out

Question: The Khmer Rouge contains mass graves.
Options:
A. true, B. false, C. uncertain
Answer: "A"