A one litre flask is full of reddish brown bromine fumes. The intensity of brown colour of vapour will not decrease appreciably on adding to the flask some :

A one-litre flask is filled with reddish brown bromine fumes. The intensity of the brown colour of the vapour will not be reduced significantly by adding some to the flask: marble shards

Because marble  $\left({\mathrm{CaCO}}_3\right)$ do not react, absorb or dissolve  ${\mathrm{Br}}_2$ . As such, there is no change in the colour of  the ${\mathrm{Br}}_2$ and ${\mathrm{Br}}_2$ dissolve partially in the water

Hence, the correct option is A.