Which of the following statements are incorrect?
I. Larger solid particles can be separated from smaller ones by filtration.
II. Cream can be separated from milk by centrifugation
III. A mixture of mud and water can be separated by loading, sedimentation and decantation
IV. Grains can be separated from husk by threshing

Options

A. I and II only
B. II and IV only
C. I, II and III only
D. I and IV only

Explanation

To determine which of the statements are incorrect, let's analyze each statement one by one.

**Step 1: Analyze Statement I**
- Statement I: "Larger solid particles can be separated from smaller ones by filtration."
- **Analysis**: Filtration is a process used to separate solids from liquids or gases using a filter medium that allows the fluid to pass but not the solid particles. However, filtration is typically used for separating solids from liquids, not for separating larger solids from smaller solids. Therefore, this statement is incorrect.

**Step 2: Analyze Statement II**
- Statement II: "Cream can be separated from milk by centrifugation."
- **Analysis**: Centrifugation is a method that uses centrifugal force to separate components of different densities. Cream, being less dense than milk, can indeed be separated from milk using this method. Therefore, this statement is correct.

**Step 3: Analyze Statement III**
- Statement III: "A mixture of mud and water can be separated by loading, sedimentation, and decantation."
- **Analysis**: This process involves adding a substance (loading) to the mixture to help the solid particles settle (sedimentation), and then pouring off the clear liquid (decantation). This method is effective for separating mud from water. Therefore, this statement is correct.

**Step 4: Analyze Statement IV**
- Statement IV: "Grains can be separated from husk by threshing."
- **Analysis**: Threshing is a process used to separate grains from their husks. It is commonly used in agriculture to separate the edible part of the grain from the inedible husk. Therefore, this statement is correct.

**Conclusion: Identify Incorrect Statements**
- The incorrect statements are:
- Statement I: "Larger solid particles can be separated from smaller ones by filtration." (Incorrect)
- Statement IV: "Grains can be separated from husk by threshing." (Correct)

Thus, the incorrect statement is only Statement I.

### Summary of Incorrect Statements:
- Statement I is incorrect.