In this paper, we propose a best proximity point theorem for a novel class of non-self-mappings by using the definition of a pair (F , h) of upper class of type II and the concept of C-class functions. Several consequences (including the case of self-mappings) of our obtained results are suggested. We support our obtained results by concrete examples. In the end, we consider an integro-differential system of equations. We ensure the existence of an optimal solution, which turns to be an exact solution of the system when boundary conditions are equal.