Final answer:
The sociocultural context and societal norms regarding nut consumption are the best predictors of how much Molly and Marvin will eat, according to Rozin and colleagues' research on portion size.
Step-by-step explanation:
Based on Rozin and colleagues' research on portion size, the best predictor of how much Molly and Marvin will eat is c) The societal norms regarding nut consumption. This research suggests that despite personal factors such as the type of nuts available, individual hunger levels, and personal preferences for nuts, the amount people consume is largely shaped by the social context and the portion sizes deemed normal in their society.
Furthermore, understanding that nutritional needs and preferences are often socially constructed can help explain why different societies may have varied expectations about food consumption, thereby influencing how much individuals like Molly and Marvin will eat in their respective environments.