Which of the following is a correct relation?

What is absolute refractive index? On what factors does it depend?

An observer can see through a pin-hole the top end of a thin rod of height $h$,placed as shown in the figure. The beaker height is $3h$ and its radius is $h$. When the beaker is filled with a liquid up to a height $2h$,the observer can see the lower end of the rod. Then the refractive index of the liquid is

$A$ tank is filled with benzene to a height of $120 \,mm$. The apparent depth of a needle lying at the bottom of the tank is measured by a microscope to be $80 \,mm$. The refractive index of benzene is: (in $.5$)

If $\hat{i}$ denotes a unit vector along the incident light ray,$\hat{r}$ a unit vector along the refracted ray into a medium of refractive index $\mu$,and $\hat{n}$ a unit vector normal to the boundary of the medium directed towards the incident medium,then the law of refraction is:

Assertion $(A)$: The colour of radiation does not change on passing through different media.
Reason $(R)$: The media do not absorb or emit colours.