Final answer:
The symbol in the context given that represents rationality and reason is Piggy's glasses, which signify enlightenment and the power of intellectual endeavor in 'Lord of the Flies'.
Step-by-step explanation:
The symbol that represents rationality and reason in the context given is Piggy's glasses. In literature, objects that characters use or interact with often carry symbolic weight. Piggy's glasses in Lord of the Flies are a prime example, signifying enlightenment, wisdom, and the power of science and intellectual endeavor in society.
They are used to create fire, which is essential for survival, and their condition throughout the novel mirrors the state of social order and rational thought amongst the boys. On the other hand, the other options listed, such as the pig's head or the fire, represent different themes such as savagery and necessary survival, respectively.