Eradicants are often used:

Eradicants are medications or treatments used to eliminate pests or pathogens after an outbreak has occurred, rather than to prevent such occurrences. The correct answer encompasses various scenarios where eradicants may be applicable.

First, eradicants may be favored when protectants are too expensive or not available because, in such instances, they become a necessary alternative to address an immediate pest problem or disease. Protectants are typically preventive measures, so their absence can necessitate the use of eradicants to control an existing problem.

Time sensitivity plays a significant role as well. When protectants have not been applied on time, the situation may allow pests or diseases to establish themselves, making it essential to use eradicants to mitigate damage or spread.

Most notably, when a disease outbreak occurs unexpectedly, eradicants are crucial for rapid intervention to control and eliminate the established problem before it exacerbates or spreads further. This option reflects the urgent need to address unforeseen circumstances where prevention was unsuccessful or absent.

By acknowledging all these scenarios, it becomes clear that eradicants serve as a vital tool in the pest control arsenal, especially when proactive measures fail or when pests/diseases become apparent.