The last two years , Derrick Burgess has been the Raiders ' most productive defensive lineman . But with a lingering calf injury that began nearly a month ago , the Pro Bowl end is lucky just to get on the practice field . He 's not the only Oakland defensive lineman hurting , either .

Based on the preceding passage, choose your answer for question Why has the Raiders defensive line not been firing on all cylinders ?
Available options:
- They have been relocated to a new stadium ..
- They are quitting on the field ..
- They ca n't afford good players ..
- They have a star injured ..
The answer is:
They have a star injured .