Which connection would be used to describe ads that a smartphone sends as a person walks around a retail store?

Machine-to-machine (M2M) communication involves two machines exchanging data without direct human intervention, which is not the case when a person receives an ad.

Business-to-consumer (B2C) describes a business model or transaction type between a company and an individual, not the underlying technical communication pattern between devices.

In the Internet of Things (IoT) context, a machine-to-person connection describes an interaction where a machine or system directly sends information or commands to an individual, often via their personal device like a smartphone. In this scenario, the retail store's system (a machine) is delivering advertisements to a shopper's smartphone (a person), perfectly fitting this classification.

Sensor-to-device is too specific; while sensors might be involved in detecting the person, the ad delivery originates from a broader system (machine) to the person, not just a raw sensor feed to a single device.