Concept:Modifiers that describe a noun must be arranged in a clear, natural order before the noun.Explanation:The main noun in the phrase is “practice.”“Fitness” tells us the type of practice.“Twice-weekly” tells us how often the practice occurs.In English, when both a purpose word and a frequency word modify a noun, the frequency word comes first, followed by the purpose word, and then the noun.Thus, the correct order is “twice-weekly fitness practice.”The completed sentence is: “The two players protested against the twice-weekly fitness practice.”Answer:D. Twice-weekly fitness practice