新闻最后一句提及their location, so close to the pyramid，而这前一句为Those who toiled on the Great Pyramid were free and enjoyed relatively good working conditions，可知最后一句中的their指的是 workers，the pyramid指的是the Great Pyramid，故答案为B选项。

【听力原文】
Egyptian archaeologists say they have discovered tombs of workers who helped build the country's largest pyramid. As Keith Adams reports, the discovery sheds light on how they lived. The tombs made from bricks of dried mud date back 4, 500 years. According to Egypt' s head of antiquities, Zahi Hawass, they revealed far from being slaves. Those who toiled on the Great Pyramid were free and enjoyed relatively good working conditions. He says their location, so close to the pyramid, which itself a tomb for their king, proves they weren' t of the slave class.