Correct Answer : Weaker
Explanation : As the flow passes through the incident wave its Mach number decreases as it moves downstream, i.e. M2 < M1. Now this M2 becomes the upstream Mach number M1 for the reflected wave, and since the deflection angles are the same for both incident and reflected waves, while reflected shock has lower upstream Mach number, the strength of the reflected wave is weaker than the incident wave.