A hyper metal accumulator is
Arabidopsis
Plants are categorised into three groups based on their uptake of heavy metals - indicator, excluder and hyperaccumulator. Hyperaccumulator is a plant capable of growing in soils with high concentration of metals. They absorb through their roots and concentrate them in their tissues. The concentration is toxic to other species not adapted to grow on such soil. Arabidopsis belonging to the family Brassicaceae is a hyperaccumulator. Hence, the correct answer is 'Arabidopsis'.