Carbon dioxide is the gas that makes soft drinks fizzy and gives them their refreshing taste. When you open a bottle or can of soda, you often hear a fizzy sound. That is the sound of carbon dioxide gas escaping. Carbon dioxide (CO₂) is dissolved into the drink under high pressure during manufacturing. When the pressure is released (like when opening a bottle), the gas comes out of the liquid and forms bubbles — this is what gives soft drinks their sparkling and bubbly texture.

Carbon dioxide not only adds fizz, but it also enhances the taste and mouthfeel of the beverage. The slight acidity created by the gas (as it forms carbonic acid in water) gives soft drinks a tangy flavor, which balances the sweetness of the sugar or artificial sweeteners.

Let’s look at the other options to clarify:
- **Oxygen** is essential for breathing and combustion, but it’s not used in making soft drinks.
- **Nitrogen** is used in some specialty drinks like nitrogen-infused cold brew coffee, but not in typical carbonated sodas.
- **Halogens** are a group of reactive elements like chlorine and fluorine and are definitely not used in soft drinks due to their harmful nature in such contexts.

So, the next time you enjoy a fizzy soda, remember that it’s the carbon dioxide working behind the scenes to give it that delightful pop and sparkle. It’s a simple gas, but it plays a big role in making our favorite beverages enjoyable.