Which condition best describes a plant that has crossed protection?

Cross protection occurs when a plant is exposed to a less virulent strain of a pathogen, which subsequently induces resistance to a more virulent strain of the same or a related pathogen. This phenomenon leverages the plant's immune response, training it to recognize and defend against related pathogenic threats. The exposure to the initial pathogen provides a protective effect against infection by another pathogen, thereby facilitating better survival and health of the plant.

The other options do not adequately describe the concept of cross protection. Nutrient enhancement pertains to growth promotion rather than pathogen resistance. Genetic resistance involves inherent characteristics of the plant that render it less susceptible to certain infections, but it does not arise from prior exposure to another pathogen. Complete freedom from infections suggests an absolute state which is generally unrealistic; even resistant plants can still experience infections under certain conditions.