The diversity of organic molecules is due to all of the following except the fact that:

Options

A. carbon needs four electrons to complete its outer shell
B. carbon can form single and double bonds with itself and other elements
C. organic molecules always contain covalent bonds
D. carbon can bond with as many as four other elements

Explanation

To solve the question regarding the diversity of organic molecules, we need to analyze the statements provided and determine which one does not contribute to the diversity of organic molecules.

### Step-by-Step Solution:

1. **Understanding Carbon's Valency**:
- Carbon has an atomic number of 6, which means it has 4 electrons in its outer shell. To achieve a stable configuration (octet), carbon needs to bond with other atoms to gain 4 more electrons.
- This statement is true and contributes to the diversity of organic molecules.

2. **Bonding Capabilities of Carbon**:
- Carbon can form single, double, and triple bonds. However, it does not form double bonds with itself.
- This statement is misleading because while carbon can form various types of bonds with other elements, it does not double bond with itself. Thus, this statement does not contribute to the diversity of organic molecules.

3. **Presence of Covalent Bonds**:
- All organic molecules contain covalent bonds, which are formed when atoms share electrons. This is a fundamental characteristic of organic compounds and contributes to their diversity.
- This statement is true.

4. **Carbon's Ability to Bond with Multiple Elements**:
- Carbon can bond with up to four other atoms, which allows for a vast array of organic molecules. This bonding capability is crucial for the diversity of organic compounds.
- This statement is also true.

### Conclusion:
The statement that carbon can form double bonds with itself is incorrect and does not contribute to the diversity of organic molecules. Therefore, the correct answer to the question is the second statement.

### Final Answer:
The diversity of organic molecules is due to all of the following except the fact that carbon can form double bonds with itself.

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