Why is bromine used as a flame-retardant instead of for water purification?

[chewchun]

Homework Statement

1:Over half a million tonnes of bromine are manufactured annually and are mainly used for making other compounds. One important use is for agricultural chemicals.
What is another important use for bromine?
a)antiseptic agents
b)bleaches for textiles and the paper industry
c)flame-retardants and fire extinguisher
d)water purification

Homework Equations

The Attempt at a Solution

I chose D but answer i got from my teacher is C.
I went to read up on the internet and the use of bromine for water treatment seems to be a alternative to chlorine...
And so,I assumed bromine to behave like chlorine...
So if C is the answer,what is the condition for a substance to be used as fire extinguisher?And why isn't D an good answer ?

 

[Borek]

Just because bromine is a potential replacement for chlorine in water treatment doesn't mean it is used for that purpose - as far as I know the only widely used systems are based on Cl₂ and O₃.

 

[AGNuke]

You can always use Wikipedia to search for your answer, it usually satisfies your queries.

Bromine as flame retardant