Answer:
A.
Step-by-step explanation:
Full-service advertising agency is an agency that is meant to handle all aspects of business, that is, advertising, marketing, and promotion. The other services that a full-service advertising agency provides are strategic planning, content marketing, SEO, production, creativity, social media marketing, etc.
The characteristic of a full-service advertising agency listed in the given options is that it is not limited to promotional activities only. As the name suggests, it offers full-fledged marketing service.
Therefore, option A is correct.