Final answer:
A/B testing is a common feature of email marketing platforms, allowing marketers to compare the performance of different email components to optimize campaigns. Other options like inventory management and employee scheduling are not typical features of email marketing tools.
Step-by-step explanation:
When it comes to email marketing platforms, one common feature that users can expect is A/B testing. This function allows marketers to create two versions of an email (Version A and Version B) to test different components such as subject lines, email content, images, or call-to-action buttons. The idea is to send these different versions to a small percentage of the total email list to see which one performs better based on predefined metrics like open rates or click-through rates. Then, the version that performs the best is sent to the remainder of the list, ensuring a more effective email campaign.
Payment processing, inventory management, and employee scheduling are features that are commonly found in other types of platforms such as e-commerce systems or human resources software, and they are not typically associated with email marketing platforms.