You want to understand if users use their mobile phone to access your site. Which of the following approach is preferable?

• A. Ask "Are you using a mobile phone to access our site?" Yes/No
• B. Ask "Which type of device are you using to access our site?" with choices: Desktop computer/Mobile Phone/Tablet
• C. Look at the report Audience/Mobile/Overview
• D. This cannot be known because people use multiple devices to browse the Web