Explanation:

The correct answer is option 'D', which states that stacking is an incorrect operation in the manufacturing of bricks.

Reasoning:

Brick manufacturing involves several steps and operations to ensure the production of high-quality bricks. These operations are carried out in a sequential manner to achieve the desired results. Let's discuss each operation in detail:

a) Preparation of Soil:
Before the manufacturing process begins, the soil is carefully selected and prepared. The soil should have a balanced composition of clay, silt, and sand to ensure the strength and durability of the bricks. The soil is thoroughly mixed with water to form a homogeneous mixture that is suitable for brick production.

b) Moulding:
Moulding is a crucial step in brick manufacturing. It involves shaping the prepared soil mixture into the desired brick shape using a mould. The moulds can be made of metal or wood and are designed to give the bricks their specific dimensions and patterns. The soil mixture is compacted and pressed into the moulds to ensure proper shape and density.

c) Drying:
After moulding, the bricks are left to dry in the open air. This process is essential as it removes excess moisture from the bricks and strengthens them. Proper drying prevents cracking or warping of the bricks during the firing process. The duration of drying varies depending on the weather conditions and the size of the bricks.

d) Stacking:
Stacking is not a correct operation in the manufacturing of bricks. This option is incorrect because stacking is an essential step in the brick manufacturing process. After the bricks are dried, they are carefully stacked in rows or layers. Stacking allows for efficient firing in the kiln and helps in the uniform heating of the bricks. It also facilitates easy transportation and storage of the bricks.

In conclusion, all the operations mentioned in the question are correct in the manufacturing of bricks except for stacking. Stacking plays a vital role in the overall process and is necessary for efficient production of high-quality bricks.