The feature of the nave of Salisbury Cathedral that is not French Gothic in character is:
Oc. Color contrast
In French Gothic architecture, color contrast is not a prominent characteristic. French Gothic style emphasizes the use of stained glass windows, intricate tracery, and detailed sculptures, rather than focusing on color contrast within the architectural elements like the nave walls or columns.
In contrast, color contrast is more commonly associated with other architectural styles or periods where contrasting colors are intentionally used to highlight architectural details or create visual interest. Therefore, among the options given, color contrast stands out as not typically associated with French Gothic architecture.