Arrange the following in a proper sequence for the extraction of petroleum.
(a) Processing of crude oil to remove heavy oil.
(b) Heating of the crude oil containing pure mixture of hydrocarbons over a specific range of temperature.
(c) Separation of constituents by fractional distillation.
(d) Purification of crude oil containing salt water.
(e) Drilling of the oil through the various layers under the earth's surface.