[单选题]
Light enters a substance frbhf -dxw t-ld(r/ac*0o dkvy0+(i- hwplt1fyzm;4/*vu5r y nhm air at $30.0^{\circ}$ to the normal. It continues through the substance at $23.0^{\circ}$ to the normal. What would be the critical angle for this substance?
A. $53.0^{\circ}$
B. $51.4^{\circ}$
C. $36.7^{\circ}$
D. $12.6^{\circ}$
