Correct Answer: A
Explanation:
To fulfill the requirement that sales managers must approve sales quote proposals both via email and on a mobile device, the best approach is to add an 'Approve/Reject' step in the workflow and enable capabilities for both email and mobile approval. This configuration allows sales managers to respond to approval requests directly from their email or through a mobile app, ensuring that the approval process is flexible and accessible across platforms, thus improving the workflow's efficiency and responsiveness.