What feature allows spores to withstand unfavorable conditions?

Spores are specialized reproductive structures that can remain dormant and resilient in unfavorable environmental conditions. The correct choice describes the presence of waxy outer shells, which play a crucial role in the survival of spores.

The waxy outer shells serve as a protective barrier, preventing desiccation or dehydration, thus enabling the spores to resist extreme temperatures, chemicals, and other adverse conditions. This feature is significant because it allows spores to survive for long periods until they encounter favorable conditions for germination and growth.

While other structural adaptations like thick membranes, multiple nuclei, and hardened cell walls may contribute to the resistance of various cells or organisms, the specific characteristic of a waxy outer shell is essential for spores' ability to endure and survive through challenging environments, making it the most appropriate choice in this context.