Coming off their easy home win over the Rams, the Ravens flew to Ralph Wilson Stadium for a Week 7 duel with the Buffalo Bills.  This game would be notable for RB Willis McGahee, as he returned to Buffalo to play against his former team.  Also, with McNair still out with injuries, QB Kyle Boller was given the start. In the first quarter, Baltimore trailed early as Bills kicker Rian Lindell got a 29-yard field goal for the only score of the period.  In the second quarter, the Ravens continued to struggle as Lindell increased Buffalo's lead with 26-yard and a 35-yard field goal.  In the third quarter, Baltimore got back into the game as McGahee ran 43 yards for a touchdown.  However, the Bills responded with Lindell getting a 41-yard field goal, along with RB Marshawn Lynch getting a 1-yard TD run.  In the fourth quarter, the Ravens got within striking range as Boller completed a 15-yard TD pass to WR Derrick Mason.  Buffalo held on to get the win.
Question: How many yards was Derrick Mason's touchdown reception?
Answer: 15