Correct Answer - Option 4 : 33%

__Concept:__

Void ratio (e): Void ratio is usually defined as the ratio of the volume of voids to the total volume of soil solid.

Porosity (n): Porosity is defined as the ratio of the volume of voids to the total volume of the soil.

The relationship between void ratio and porosity are as follows:

\(\rm{e=\frac{n}{1-n}\; and\; n=\frac{e}{1+e}}\)

__Solution:__

Void, Ratio, e = 0.5

Porosity, \(n=\frac{e}{1+e}\)

η = 0.5/1.5 = 0.33