Which choice indicates that the soda lime granules in a CO2 absorbent canister have become exhausted?

The correct choice indicates that the soda lime granules in the CO2 absorbent canister have undergone a significant chemical change indicating exhaustion. In this context, soda lime typically changes color to indicate its effectiveness in absorbing CO2. When the granules are fresh and functional, they are generally white. Over time, as they absorb carbon dioxide, they may change color, often to a hue suggesting they are no longer able to effectively capture CO2.

In particular, the change from white to purple signifies that the absorbent material has reached a saturation point and thus is exhausted. This color change is a visual cue for veterinary technicians and other professionals to monitor and ensure proper functioning of the anesthetic equipment.

The other choices do not represent what happens upon expiration of the absorbent's efficacy. For instance, if the color stays pink or remains white, it suggests either that the granules have not yet absorbed enough CO2 to indicate saturation or that they are still functional. Thus, monitoring for the purple hue is crucial for safety and effective patient anesthetic management.