Final answer:
The correct answer is d) Assignment, as assignments have work or duration values in project management.
Step-by-step explanation:
The answer to the question 'Only a(n) _________ can have a remaining work or duration value.' is d) Assignment. In project management terminology, specific assignments made to team members or resources are what can have remaining work or a duration value. A summary task is a collection of subtasks and typically reflects the total values of its subtasks rather than having its own independent duration. A subtask is a division of a summary task and has its own work and duration values. A milestone marks a significant point or event in a project and is generally set to have zero duration.