_____________ bacterium can withstand the dosage of radiation, which are several times higher than what human cells can tolerate

The correct option is Deinococcus radiodurans.

Deinococcus radiodurans is an extremophilic bacterium renowned for its extraordinary resistance to ionizing radiation. While a dose of 5 to 10 grays (Gy) is lethal to human cells, D. radiodurans can withstand radiation doses of up to 15,000 Gy without dying or losing its ability to reproduce.
This extreme resistance is primarily due to its highly efficient DNA repair mechanisms (such as homologous recombination) and multiple copies of its genome, which allow it to rapidly stitch back together chromosomes shattered by intense radiation.