Final answer:
Firms' promotional objectives often focus on enhancing brand familiarity by increasing the number of customers who insist on a brand.
Step-by-step explanation:
According to the information provided, the correct statement about marketing and social media is option C. Firms' promotional objectives often focus on enhancing brand familiarity by increasing the number of customers who insist on a brand. This means that firms use social media platforms to build brand recognition and loyalty among customers.