Psychologists recently conducted a study in which people from widely disparate cultures were asked to examine five photographs. Each photograph depicted the face of a person expressing one of five basic human emotions -- fear, happiness, disgust, anger, and sadness. The people in the study were asked to identify the emotion being expressed in each photograph. For each photograph, everyone identified the same emotion. This shows that people are genetically predisposed to associate certain facial expressions with certain basic emotions. Which one of the following is an assumption on which the argument depends? ['If there is a behavior common to people of widely disparate cultures, then there is probably a genetic predisposition to that behavior.', "One's emotional disposition is not influenced by one's culture.", 'For each photograph, the emotion that the subjects agreed was being expressed was the emotion that the person photographed was, in fact, feeling.', 'The people whose faces were depicted in the photographs were not all from the same culture.']