Answer:
A. Portable people meter
Explanation:
The portable people meter also called the Nielsen meter or PPM for short is a device used to define listening habits on behalf of radio stations across the United states of America. It records media when it is being used and by who is using it. It's like a pager like device in which people carry out through out the day. The Nielsen then uses data it gets to produce monthly ratings of local reports for each markets.
