What characteristic is true regarding bacteria?

Bacteria are unicellular organisms that reproduce primarily through a process called binary fission. This is an asexual reproduction method where a single bacterial cell divides into two identical daughter cells. This characteristic is fundamental to bacterial life and contributes to their ability to multiply rapidly under favorable conditions.

On the other hand, the other provided options are not applicable to the nature of bacteria. Bacteria do not have a multicellular structure, as they are typically single-celled. They also lack a nucleus since they are prokaryotic organisms, meaning their genetic material is not enclosed within a membrane-bound nucleus. Furthermore, while some bacteria are photosynthetic and can utilize sunlight, many do not require sunlight for their growth and can thrive in various environments, including dark and nutrient-rich substrates.