In the given sentence, the word liability suggests a negative aspect or a hindrance for the factory due to the equipment's old age. To maintain the original meaning of the sentence, we need a synonym that conveys a similar negative connotation.
Let's examine the provided options:
- Cost: Refers to the amount that must be paid or spent to buy or obtain something. It doesn't specifically carry a negative connotation indicating a drawback or hindrance.
- Disadvantage: Refers to an unfavorable circumstance or condition that reduces the chances of success or effectiveness. This aligns well with the meaning of liability, which denotes a drawback.
- Aid: Refers to assistance, support, or help. This has a positive connotation, opposite to what is required.
- Capacity: Refers to the maximum amount that something can contain or produce. This is unrelated to the context of a drawback or a hindrance.
Thus, the word disadvantage best captures the meaning of liability in the sentence's context.
The correct answer is disadvantage.