Final answer:
Pregnant women should avoid King mackerel because it contains high levels of mercury, which the EPA advises against for pregnant women and young children due to the dangers of biomagnification.
Step-by-step explanation:
A pregnant woman should avoid consuming King mackerel due to its high mercury content. According to advice from the United States Environmental Protection Agency (EPA), pregnant women and young children should not eat swordfish, shark, king mackerel, or tilefish because of the risk of mercury exposure through biomagnification. Instead, they should opt for fish that are low in mercury such as salmon, tilapia, shrimp, pollock, and catfish.