The correct answer is $\boxed{\text{B}}$. Chlorine is a non-metal.
A metalloid is a chemical element with properties that are in between those of metals and non-metals. Metalloids are typically semiconductors, which means that they conduct electricity better than non-metals but not as well as metals. They also have a higher melting point than non-metals but a lower melting point than metals.
Boron, arsenic, and silicon are all metalloids. They are all semiconductors and have a higher melting point than non-metals but a lower melting point than metals. Chlorine, on the other hand, is a non-metal. It is not a semiconductor and has a lower melting point than all of the metalloids.