The correct answer is A. Maxwell’s equations.
Maxwell’s equations are a set of four partial differential equations that form the basis of classical electromagnetism, classical optics, and electric circuits. They describe how electric and magnetic fields are generated and altered by each other and by charges and currents.
Maxwell’s equations can be used to derive the wave equation for electromagnetic waves, which states that the electric and magnetic fields of an electromagnetic wave propagate at the speed of light. This makes Maxwell’s equations the most appropriate equations for the study of electromagnetic wave propagation.
Allen-Cahn equations are a set of partial differential equations that describe the evolution of phase boundaries in a system. They are used in a variety of fields, including physics, chemistry, and materials science.
Avrami equations are a set of equations that describe the kinetics of phase transformations. They are used in a variety of fields, including materials science, metallurgy, and chemical engineering.
Boltzmann’s equations are a set of equations that describe the distribution of particles in a system. They are used in a variety of fields, including physics, chemistry, and statistical mechanics.