Mark the incorrect statement .

Options

A. Inner orbital (low spin) complexes involve `d^(2) sp^(3)` hybridisation .
B. Outer orbital (high spin) complexes involve `sp^(3) d^(2)` hybridisation .
C. Tetrahedral complexes generally involve `dsp^(2)` hybridisation .
D. Stereoisomerism involves geometrical and optical isomerism .

Explanation

To solve the question of identifying the incorrect statement regarding coordination compounds, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement 1: Inner orbital complexes involve d²sp³ hybridization.**
- **Analysis:** Inner orbital complexes are those that utilize the 3d orbitals for bonding. The hybridization d²sp³ is indeed characteristic of inner orbital complexes. Therefore, this statement is **correct**.

2. **Statement 2: Outer orbital complexes involve sp³d² hybridization.**
- **Analysis:** Outer orbital complexes do not use the 3d orbitals for bonding. Instead, they typically involve hybridizations like sp³d². Thus, this statement is also **correct**.

3. **Statement 3: Tetrahedral complexes generally involve dsp² hybridization.**
- **Analysis:** Tetrahedral complexes are characterized by sp³ hybridization, not dsp². The dsp² hybridization is associated with square planar complexes. Therefore, this statement is **incorrect**.

4. **Statement 4: Stereoisomers involve geometrical and optical isomers.**
- **Analysis:** Stereoisomers indeed include both geometrical isomers (cis/trans) and optical isomers (enantiomers). Hence, this statement is **correct**.

### Conclusion:
The incorrect statement among the options provided is **Statement 3**. Therefore, the answer is **C**.

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