The Steelers stayed home for Game 2 of a 3-game home stand against the Raiders.  In the first quarter, the Raiders scored first as Derek Carr found Michael Crabtree on a 22-yard pass for a 7-0 lead.  The Steelers got on the board later on in the quarter when Chris Boswell kicked a 34-yard field goal for a 7-3 game.  In the 2nd quarter, the Steelers took the lead when DeAngelo Williams ran for a TD from 3 yards out (with a successful 2-point conversion) for an 11-7 game.  The Raiders however, retook the lead when Carr found Amari Cooper on a 15-yard pass for a 14-11 lead.  The Steelers closed the half when Williams ran for another 3-yard TD and Boswell kicked a 38-yard field goal for leads of 18-14 and then 21-14 at halftime.  After the break, the Raiders went back to work tying the game up 21-21 when Carr found Clive Walford on a 1-yard pass for the only score of the third quarter.  In the fourth quarter, the Steelers were able to retake the lead as Ben Roethlisberger found Martavis Bryant on a 14-yard pass for a 28-21 game.  Roethlisberger then found Jesse James on a 4-yard pass for a 35-21 game.  The Raiders would tie the game back up with 2 straight TDs of their own:  First coming from Jamize Olawale who ran from 19 yards out for a 35-28 game and then Carr finding Crabtree again on a 38-yard pass to make it 35-35.  Getting the ball back with seconds left, the Steelers had to depend on backup QB Landry Jones to help them get within field goal range.  They would successfully do so and then Boswell kicked the game-winning 18-yard field goal for a 38-35 final score.
Question: How many TD passes did Carr throw?
Answer: 4