Researchers hope to find clues about the A' mk peoples who lived in the Kaumpta region about one thousand years ago but who left few obvious traces. The researchers plan to hire the few remaining shamans of the modern-day indigenous people in Kaumpta, who are believed to be descended from the A' mk, to lead them to ancestral sites that may be the remains of A' mk buildings or ceremonial spaces. The shamans were taught the location of such sites as part of their traditional training as youths, and their knowledge of traditional Kaumpta customs may help determine the nature of any sites the researchers find. Which of the following is an assumption on which the success of the plan depends? ["The shamans have a reasonably accurate memory of A'mk sites they learned about as youths.", "Most or all A'mk sites are likely to be found within the Kaumpta region.", 'Kaumpta shamans are generally held in high esteem for their traditional knowledge.', "The researchers have reliable evidence that the A'mk of one thousand years ago built important ceremonial spaces."]