Answer:
b. ancient
Step-by-step explanation:
Although all of these words have very similar meanings, they are not exactly the same. Therefore, they are not interchangeable. "Aged" refers to something that has been left on purpose so that it becomes improved as time passes. "Ancient" refers to something that comes from the far past. "Geriatric" refers to something related to the elderly, while "old" refers to something that is showing signs of use or that is no longer new.