A materials company tests three gas samples with bromine water before selecting a sample to use as a raw material for making polymers. The results are shown in the table.
| Gas sample | Result with bromine water |
|---|---|
| A | Bromine water remains orange |
| B | Bromine water changes from orange to colourless |
| C | Bromine water remains orange |
Which gas sample should the company select? Explain your choice.