Final answer:
User roles in Marketo customize B. the views and permission levels available for Marketo users, controlling their access to features and data while maintaining security and appropriate access based on their job functions.
Step-by-step explanation:
The question pertains to the customization of user roles within the Marketo platform. User roles in a system like Marketo allow for the management and specification of what users can see and do within the software. The correct answer to which aspect user roles permit you to customize is B. The views and permission levels available for Marketo users.
This is because user roles are designed to control access to different features and data within Marketo, ensuring that users have the necessary permissions to perform their job functions without having access to sensitive information that doesn't pertain to their role. Customizing user roles does not directly affect campaign operation, landing page appearance, or marketing suspend duration. These areas are typically managed through other settings within the Marketo platform.