Answer:
The correct answer is letter "D": message customization without high costs of personal selling.
Step-by-step explanation:
Social media marketing has made it easy for companies to spread their advertisement. Resources used for marketing campaigns through social media could be cheaper compared to other mediums of information such as television or billboards. Besides, personalized ads in the form of messages or e-mails are likely to reach target consumers faster because of the massive use of mobile devices.