A point source S is placed at the bottom of a transparent block of height 10mm and refractive index 2.72 it is immersed in a lower refractive index liuiqd as shown in the figure. It is found that the light emerging from the block to the liquid forms a circular bright spot of diameter 11.54 mm of the top of the block. the refractive index of the liquid is
A. 1.21
B. `1.30`
C. `1.36`
D. `1.42`