Answer C sounds good to us. "Strident," "earsplitting," and "raucous" all refer to something that is marked by a high intensity or volume of sound. "Strident," our word today, is the most formal of the three words and implies a harsh but insistent quality, especially in a voice ("the strident voice of the coach on the sidelines"). "Earsplitting" is used of sound that is so loud or harsh that it could hurt your ears ("an earsplitting siren"). "Raucous," the most commonly used of the three synonyms, suggests that the harshness of the sound (usually a voice) is because of rowdiness ("a raucous party that kept the neighbors awake all night").