Refer to the Figure

Refer to the figure.
The top figure shows concentrations of PCBs in killer whales and harbor seals at several locations. The bottom figure shows concentrations of PBDEs in both groups of mammals. These persistent organic chemicals build up in animal tissues and disrupt their endocrine systems, including reproductive systems. What is the most reasonable conclusion that can be drawn regarding the effect of these chemicals based on the data in these figures?

A) The levels of both types of chemicals have been high, but are now decreasing.
B) The levels of both types of chemicals vary by population, but some are dangerously high.
C) The levels of both types of chemicals are often high, but never dangerously so.
D) In most cases, harbor seals appear to concentrate and remove the chemicals, where killer whales do not.