Which of the following posses allylic H-atom ?

Options

A.
B.
C.
D.

Explanation

To determine which of the given structures possesses allylic hydrogen atoms, we first need to understand what an allylic hydrogen atom is. An allylic hydrogen is a hydrogen atom that is attached to a carbon atom adjacent (alpha) to a carbon-carbon double bond.

### Step-by-Step Solution:

1. **Identify the Double Bond**: Look at each structure provided in the options and identify the location of the double bond.

2. **Determine Alpha Carbons**: For each double bond, identify the two carbon atoms directly involved in the double bond. These are referred to as the "double bond carbons."

3. **Locate Allylic Carbons**: The carbon atoms that are directly adjacent to the double bond carbons are called the "allylic carbons." There will be two allylic carbons for each double bond.

4. **Check for Hydrogen Atoms**: Examine the allylic carbons to see if they have hydrogen atoms attached. If an allylic carbon has at least one hydrogen atom, then it possesses allylic hydrogen.

5. **Evaluate Each Option**:
- **Option 1**: Check the structure for allylic hydrogens. If both allylic carbons lack hydrogen, this option is incorrect.
- **Option 2**: Repeat the process for this structure. If neither allylic carbon has hydrogen, this option is also incorrect.
- **Option 3**: Again, check for hydrogen on the allylic carbons. If neither has hydrogen, this option is incorrect.
- **Option 4**: In this structure, check the allylic carbons. If at least one of them has hydrogen, this option is correct.

6. **Conclusion**: Based on the evaluations, the option that contains allylic hydrogen atoms is the correct answer.

### Final Answer:
The correct option that possesses allylic hydrogen atoms is **Option 4**.