A light ray travels from a dense optical medium (glass) into a less dense medium (air) and is incident at the boundary at an angle $\theta_i$. The critical angle $\theta_c$ is the minimum angle at which total internal reflection (TIR) occurs.

A light ray travels from a dense optical medium (glass) into a less dense medium (air) and is incident at the boundary at an angle $\theta_i$. The critical angle $\theta_c$ is the minimum angle at which total internal reflection (TIR) occurs.

Which of the following changes will ensure that total internal reflection occurs for the light ray at the glass-air boundary, as shown in the image below?