CMAT Exam 2023 Shift 1 Solved Paper

The use of "has" as the auxiliary verb in this sentence is appropriate because it indicates an action that started in the past and continues into the present. The phrase "for many years" suggests a duration of time, indicating that the use of CCTV for surveillance has been ongoing. The auxiliary verb "has" is used with the third-person singular subject "CCTV" to form the present perfect tense, which is suitable for describing an action that began in the past and has a connection to the present.