The relation between the refractive index and the optical density of the material is a direct relation.
This means that the more the refractive index is, the more optically dense the material is.
Based on the above, when checking the given choices, the refractive index that represents the most optically dense material would be the largest refractive index which is:
<span>d. 2.65</span>
Velocity (v) is a vector quantity that measures displacement (or change in position, Δs) over the change in time (Δt), represented by the equation
v = Δs/Δt.
Conduction has to be touching the two objects. Convection is not direct.