Which among the following method is used to obtain petr

SOLUTION

If the difference between the boiling points of the mixture of miscible liquids is less than $25{}^{\circ }\text{C}$, then fractional distillation is used to separate components of the mixture.

Crude oil which is drilled out from the depth of the Earth, is a mixture of hydrocarbons (petrol, kerosene, diesel etc.) and the difference in the boiling points of these components is less than $25{}^{\circ }\text{C}$.
Hence, fractional distillation is the method used to obtain the different components (petrol, kerosene, diesel etc.) from crude oil.