Write the next sentence in this paragraph:

How to be safe when using a chemistry lab
Be smart about chemicals and the dangers they pose.
Some chemicals are harmless; others can kill you! Until you are familiar with the chemicals you are using in the lab, always ask an instructor for help. There are a few basic points about chemical safety to bear in mind :
Never mess with an unlabeled chemical.

Available options:
1). It may be corrosive and dangerous to your skin, and mixing it with other chemicals could produce toxic fumes or even an explosion. Know the difference between an acid and a base..
2). Chemicals can be harmful to humans and bio-humans, especially some pet plant-based counterparts. You should choose chemicals with effects similar to those found in a chemical lab, such as mineral sulfate, nitrites, etc..
3). On the surface it might look sort of funny, but on the inside it's not. You're sensitive to the fumes..
4). It is best not to identify one as the first one. Consult a medical doctor when there are any public-regulation concerns related to chemicals..
1).