Answer:
Sewage treatment generally involves three stages, called primary, secondary and tertiary treatment. Primary treatment consists of temporarily holding the sewage in a quiescent basin where heavy solids can settle to the bottom while oil, grease and lighter solids float to the surface.
Explanation:
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Number of types of bread for making sandwich = 2
Number of types of meat for making sandwich = 3
Number of types of cheese for making sandwich = 2
Then
Number of different sandwiches that can be made = 2 * 3* 2
= 12 sandwiches
From the above deduction, it can be easily concluded that the correct option among all the options that are given in the question is the first option.
