The correct answer is B. Chlorine.
Magnesium, sodium, and aluminium are all metals. Metals are elements that are typically shiny, have a high luster, and are good conductors of heat and electricity. They are also malleable, meaning they can be easily shaped.
Chlorine is a non-metal. Non-metals are elements that are typically dull, have a low luster, and are poor conductors of heat and electricity. They are also brittle, meaning they break easily.
Here is a table that summarizes the properties of metals and non-metals:
| Property | Metal | Non-metal |
|—|—|—|
| Appearance | Shiny | Dull |
| Luster | High | Low |
| Conductivity of heat and electricity | Good | Poor |
| Malleability | Easy to shape | Brittle |
I hope this helps! Let me know if you have any other questions.