What does it mean for a bacterium to multiply?

When a bacterium multiplies, it specifically refers to the process of reproduction and the subsequent increase in the number of bacterial cells. This can occur through binary fission, where a single bacterium divides into two identical daughter cells. This ability to reproduce is fundamental to the survival and proliferation of bacterial populations, allowing them to occupy new environments and resources.

The other choices reflect different aspects of bacterial behavior, such as structural changes for adaptation, dormancy during unfavorable conditions, or toxin production that can lead to foodborne illness. However, these do not directly pertain to the process of multiplication itself, which is solely about increasing the number of bacteria.