One characteristic of selective media is that it:

Selective media is specifically designed to inhibit the growth of certain types of microorganisms while allowing others to thrive. This selective nature enables microbiologists to isolate particular species from a mixed culture or to enrich for organisms with specific metabolic capabilities. For example, a selective medium can contain antibiotics to suppress the growth of non-resistant bacteria, thereby allowing only resistant strains to grow. This feature is crucial in various applications, such as clinical diagnostics, environmental microbiology, and food safety testing, as it aids in the identification and study of specific microorganisms of interest in a sample that may contain diverse microbial populations.

In contrast, options that involve allowing all microbes to grow, distinguishing microbes based solely on color, or restricting growth based solely on size do not capture the essence of selective media. Selective media's primary function revolves around promoting the growth of certain microbes while inhibiting others, making it an essential tool in microbiological practices.