The correct answer is option 4, Carbon Monoxide. Carbon monoxide is not considered a greenhouse gas.

Let`s look at each option to understand why it is or is not a greenhouse gas:

1. Water vapors: Yes, water vapors are considered greenhouse gases. They contribute to the greenhouse effect by trapping heat in the Earth`s atmosphere.

2. Methane: Yes, methane is a potent greenhouse gas. It is released through natural processes like decomposition and also through human activities such as agriculture and fossil fuel extraction.

3. Ozone: Yes, ozone can act as a greenhouse gas. It is present in the Earth`s atmosphere and helps to trap heat, but it also plays a role in protecting us from harmful ultraviolet radiation.

4. Carbon Monoxide: No, carbon monoxide is not considered a greenhouse gas. It is a byproduct of incomplete combustion and does not have the ability to trap heat in the Earth`s atmosphere.

Therefore, option 4, Carbon Monoxide, is the correct answer as it is not classified as a greenhouse gas.