Which of the following is an example of a xerophilic fungus?

The correct choice highlights that both Penicillium and Aspergillus species can exhibit xerophilic characteristics. Xerophilic fungi are adapted to survive in very low water activity environments, making them capable of thriving in dry conditions.

Penicillium and Aspergillus, in particular, are well-documented genera that can tolerate and proliferate in environments with limited moisture, such as dried foods and certain agricultural products. This adaptability allows them to colonize and metabolize substances where other fungi may not survive. Their ability to grow under such stressful conditions is a defining feature of xerophilic fungi.

On the contrary, other options listed, like Aspergillus niger, Rhizopus stolonifer, and Cephalosporium acremonium, may not exhibit the same level of xerophilic adaptation. While some of these fungi can grow in a wide range of conditions, they are not primarily classified as xerophilic, as they tend to prefer higher moisture levels for optimal growth. Therefore, the combination of Penicillium and Aspergillus is the most accurate representation of xerophilic fungi in this context.