During the iteration planning, team commits to complete 5 stories worth 20 story points. However, during the iteration, it seems team would be able to complete 4 stories worth 18 story points only. As a scrum master, what should you suggest the team?
a. Since the team committed for 20 story points so the team should work overtime to meet their target.
b. Do less testing and try to complete all 5 stories
c. Complete 4 stories only worth 18 story points
d. Ask Product Owner if iteration length can be increased