Which of the following activities is primarily associated with telemarketers?

Telemarketers primarily engage in telephone sales calls as their main method of reaching customers. This approach involves contacting potential or existing customers directly via phone to promote products or services, gather leads, or conduct surveys. Telemarketing allows businesses to interact with consumers in a personal manner, providing immediate responses and the opportunity for dialogue, which can help to close sales effectively.

While door-to-door sales involve selling products in person and online advertising uses digital platforms to promote goods or services broadly, these methods do not specifically relate to telemarketing. Similarly, direct mail campaigns involve sending physical promotional materials by post, which does not utilize telephone communication. Hence, telephone sales calls are distinctly aligned with the core functions and practices of telemarketers.