What concept is closely related to the process of definite integration?

The concept of "Limit of a Sum" is fundamental to the process of definite integration because it lays the groundwork for understanding how integration is defined. Definite integration can be viewed as the limit of a Riemann sum, which approximates the area under a curve by dividing it into smaller rectangles.

When you take the limit as the width of these rectangles approaches zero, the Riemann sum converges to the exact area under the curve, which is what definite integration computes. This relationship shows how integration can be understood as the accumulation of infinitesimally small quantities, which is a core idea in calculus.

Other options like "Partial Fractions," "Integration by Parts," and "Chain Rule" are techniques or rules used in the process of integration but do not directly relate to the foundational concept of definite integration in the same way that the limit of a sum does. These techniques help solve complex integrals, but they do not encapsulate the fundamental definition of what definite integration represents.