Which characteristic of GFP makes it valuable for visualization in biological studies?

The characteristic that makes GFP particularly valuable for visualization in biological studies is its ability to fluoresce under specific light. This property allows researchers to use GFP as a fluorescent marker, enabling them to track proteins, cells, or even entire organisms in real-time. When exposed to certain wavelengths of light, GFP absorbs that energy and emits fluorescence, allowing scientists to visualize cellular processes and dynamics in living organisms. This makes it a powerful tool for understanding biological mechanisms and interactions in various research fields, including cell biology, genetics, and developmental biology. Other characteristics, while they may enhance its usability, do not provide this fundamental capability for visualization.