In developing your next email campaign, you have to make a case to develop a responsive email. What is the key factor of responsive design to persuade your team?

• A. People open emails on smartphones more than any other device.
• B. Responsive design means designing for iPhones.
• C. People open emails multiple times on a variety of devices. So, the email needs to render properly regardless.
• D. Responsive design means mobile-first thinking.