Final answer:
The root of the word auditorium is 'aud,' originating from the Latin verb 'audire,' meaning 'to hear' or 'to listen.' The correct answer is option C.
Step-by-step explanation:
The root of the word auditorium is 'aud'. This root comes from the Latin verb 'audire,' which means 'to hear' or 'to listen.' In an auditorium, people gather to listen to performances, speeches, or presentations. Therefore, the focus on sound and listening is captured in the root 'aud,' establishing it as the primary basis of the word.