Answer: The task is deleted from the user's Inbox and a decline message is sent to the person who assigned the task.
Step-by-step explanation:
When a task is declined by a user, the task is deleted from the user's Inbox and a decline message is sent to the person who assigned the task.
On the other hand, if a user accepts an assigned task, then the task will be moved to the user's task list.
Therefore, the correct option is B.