Electrons Are in a Two-Dimensional Square Potential Energy Well with Sides

Multiple Choice

Electrons are in a two-dimensional square potential energy well with sides of length L. The potential energy is infinite at the sides and zero inside. The single-particle energies are given by where n_x and n_y are integers. At most the number of electrons that can have energy 8(h²/8mL²) is:

A) 1
B) 2
C) 3
D) 4
E) any number