The correct answer is option 3, which states that all the given statements are correct.

Let`s examine each statement to understand them better:

Statement 1: Physiological density is the measure of population per unit of arable land. Therefore, to compute physiological density, we need to divide the total population by the net cultivable area.

Statement 2: Agricultural density is the measure of the number of farmers or agricultural population per unit of arable land. To compute agricultural density, we need to divide the total agricultural population by the net cultivable area.

Statement 3: Population density is the measure of the total population per unit of area. To compute population density, we need to divide the total population by the total area, irrespective of its cultivability.

All three statements correctly describe the computation of different types of density. Therefore, the correct answer is option 3.