Radioactive Sr-$90$ can enter and accumulate in human body through _______.

The correct option is B Food chain
Strontium-90 is the radioactive fissile material that has a half-life of 28 years. It readily enters into the food chain from the soil when absorbed by the plants. Its persistent nature results in the biomagnification. Like any other radioactive waste, it is also either dumped in the soil or in the water. In both the conditions, it finds its way to the food chain by getting absorbed by the producers. It causes severe ailments especially in children like leukaemia and bone cancer.

Hence, the correct answer is 'Food chain'