The word "dynamic" typically means active, energetic, or characterized by change and progress. To find the most appropriate antonym, we should look for a word that means the opposite of active or changeable.

Option 1: "Still" means not moving or stationary. It is an appropriate antonym for "dynamic."

Option 2: "Lethargic" means lacking in energy or enthusiasm, which is similar in meaning to "still" or "static."

Option 3: "Constant" means unchanging or remaining the same, which is more related to "static" than the opposite of "dynamic."

Option 4: "Static" means lacking in movement or change. It is an appropriate antonym for "dynamic."

"Static" (Option 4) is a precise opposite.