Answer:
A is correct
Step-by-step explanation:
Since the half-life of Cesium is 30 years, that mean that passing this period of time there is going to be the half of mass of this element in ocean. Of course since day 1 until year 30, there will be plenty of generations of the marine living things, so what is going to happen is that this element can be absorb by the algae or plants from the ocean, Cesium is going to fixed in tissues, so when small fish are going to eat, they are going to accumulate Cesium in their tissues (but a bigger concentration than the producer), when another animal eat this small animal is going to repeat the process, in that way biomagnification will be a concern to humankind.