Symmetry of Net Substitution Effects Is One of the Principal

Multiple Choice

Symmetry of net substitution effects is one of the principal conclusions of the theory of utility maximization.Which two mathematical theorems are used to prove this symmetry?

A) Taylor's Theorem and Fundamental Theorem of Calculus.
B) Cauchy's Theorem and DeMonre's Theorem.
C) Lagrangian Theorem and Fundamental Theorem of Calculus.
D) Envelope Theorem and Young's Theorem.