Coming off their dominating home win over the Chiefs, the Broncos flew to Reliant Stadium for a Thursday night intraconference duel with the Houston Texans.  In the first quarter, Denver trailed early as QB Sage Rosenfels got a 5-yard TD run for the only score of the period.  In the second quarter, the Broncos would get on the board as kicker Jason Elam managed to get a 41-yard field goal.  Houston would respond with kicker Kris Brown getting a 41-yard field goal.  Denver would end the half with Elam nailing a 47-yard field goal. In the third quarter, the Texans would increase their lead as RB Ron Dayne managed to get a 6-yard TD run.  The Broncos would respond with QB Jay Cutler completing a 12-yard TD pass to TE Tony Scheffler.  However, in the fourth quarter, Houston sealed the win as Rosenfels completed a 4-yard TD pass to WR Andre Johnson, while FB Vonta Leach got a 1-yard TD run.
Question: In which quarter did the Broncos first score a touchdown?
Answer: third