Answer:
B. Expresses how effective conveying sincere gratitude and appreciation toward another person can be.
Step-by-step explanation:
In the article, the writer's diction is a comparison in the sincerity between how people express their gratitude for a service rendered. The sincerity in the way a person expresses gratitude is a measurement scale to see how really a person appreciates something. For example, the person who writes a personal handwritten note will be much more sincere than a person who sends an automated prompted email response which is just a rote method of communication.