In the Redskins' second preseason game, they scored first but not without having a scare first. On their second drive, Quarterbacks Jason Campbell was tackled at the knee while throwing a complete 29-yard pass to tight end Chris Cooley&#8212;Campbell hobbled off the field with a bruised knee. Todd Collins took over for Campbell with some early success in the game; he threw a 7-yard touchdown pass to Brandon Lloyd. The Redskins had four goal-line stands, and only allowed 12 points (four field goals). However, their offense struggled to really got back into the swing of things without Campbell; their only other score of the game was a field goal. The Redskins' sustained some injuries during the game: linebacker Marcus Washington suffered a dislocated elbow, and wide receiver Mike Espy ruptured his tendon and subsequently was out for the season due to the injury. GameBook
Question: What body part did Campbell injure?
Answer: knee