Which of the following conditions can an endospore survive?

Endospores are highly resilient structures produced by certain bacteria as a means of survival under extreme and unfavorable conditions. The correct answer highlights that endospores can survive unfavorable conditions, specifically heat and alcohol, which are typically detrimental to most bacterial cells.

Endospores are designed to endure harsh environments, possessing a tough outer coating that provides protection against extreme temperatures, desiccation, chemicals, and radiation. When conditions become suitable again, these spores can germinate and return to active growth. This unique ability to withstand high levels of heat and the presence of alcohol makes them an important factor in understanding bacterial survival strategies.

High humidity, while not ideal for all bacteria, would not generally threaten endospores, as they require conditions of desiccation or extreme temperatures for survival. Cold temperatures are typically not harmful to endospores, as many can survive freezing, but they are not the most challenging conditions they can endure. Direct sunlight can cause problems for vegetative cells due to UV radiation, but the protective shell of an endospore enables it to withstand such exposure effectively. Hence, the option that highlights survival in unfavorable conditions, such as heat and alcohol, accurately represents the unique resilience associated with endospores.