Final answer:
The phrase from The Aeneid suggests that unlike humans, who weaken with age, gods retain their toughness and vitality, meaning they may appear old but remain powerful. The correct answer is option: C. Old gods may look weak, but they stay powerful.
Step-by-step explanation:
The phrase 'old age in a god is tough and green' from line 12 of The Aeneid illustrates an ancient perspective on divinity and age, particularly relating to their enduring power and vitality. In many ancient texts, the gods are depicted as ageless and invincible, maintaining their strength and influence regardless of the passage of time.
This contrasts with human old age, often symbolized by weakness and deterioration. The phrase suggests that while human capability may decline with age, the divine retain their toughness ('tough') and vitality ('green'), even as they grow older. Therefore, the most suitable interpretation of this excerpt from The Aeneid would be that 'old gods may look weak, but they stay powerful,' aligning with choice C.