Identify the full form of the CDU.
A. Central Distillation Unit
B. Center of Distillation Unit
C. Crude Oil Distillation Unit.
D. None of these

Hint: The refining end products are classified into different distillates such as Light distillates, Middle distillates, Heavy distillates. The end products of light distillates are Liquified Petroleum Gas (LPG), light naphtha, gasoline, and heavy naphtha. Middle distillates are kerosene, automotive and railroad diesel fuels, residential heating fuel, and other light fuel oils. The Heavy distillates are heavy fuel oils, wax, lubricating oils, and asphalt. Also, coke and Elemental sulfur are the end products of the central distillation units.

Complete step by step answer:
The CDU here stands for the Crude Distillation Unit (CDU). This is the first processing unit in petroleum refineries. The crude distillation unit distills the incoming crude oil into fractions of various boiling points and each of them is then processed further in the other refinery processing units.
Thus, the full form of the CDU is Crude Oil Distillation.
Therefore, option C. is the right answer.

Note:
The Central Distillation Unit is referred to as the atmospheric distillation unit because it operates at slightly above atmospheric pressure. The desalting process and distillation of crude oil are included in the crude distillation unit (CDU). The desalting process of crude oil is imperative to ensure the good quality of crude oil, that is, to remove impurities before it transfers to refining. This procedure minimizes or eliminates harmful substances such as sulfur, water, salts, and even mechanical impurities, which ensure a long operation of pipelines. However, the desalting process is only part of the distillation unit. The other phase of this unit is distillation. Distillation is more physical than a chemical process.