Which of the following functions can be applied to the entrances and exits of shopping malls, supermarkets, chain stores, associations, and museums to count the number of people entering and exiting to assist users in analyzing laws and trends?

Which of the following functions can be applied to the entrances and exits of shopping malls, supermarkets, chain stores, associations, and museums to count the number of people entering and exiting to assist users in analyzing laws and trends?
A . People counting
B . Item removal detection
C . Intrusion detection
D . Detection of leftover items

Answer: A