Final answer:
MyPlate's key message of varying your protein routine does not specifically mandate consuming seafood once a week, but encourages a variety of protein sources.
Step-by-step explanation:
The statement that one of MyPlate's key messages is to consume seafood once a week is False. The actual key messages from MyPlate include the following:
Focus on whole fruits
Vary your veggies
Vary your protein routine
Make half your grains whole grains
Move to low-fat or fat-free milk or yogurt
While varying your protein routine is a recommendation, there is no specific message stating that you should consume seafood once a week. Instead, MyPlate encourages a variety within the protein group, which can include seafood, meat, poultry, eggs, nuts, and beans.