Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information. A. Humans using stone tools to butcher animals left marks on the bones of the animals they killed and the animals they scavenged. B. Humans scavenged animals killed by other animals and butchered them using stone tools. C. Tool marks on butchered animal bones are analyzed to help determine whether humans killed or merely scavenged the animals. D. Analysis of the stone tools used by humans to butcher scavenged animals is now being carried out.