Obstruction

[RKBUmp]

Ok, now Im confused. Taking the NFHS test and one of the questions is throw to F3 pulls her off the bag and impedes the batter/runner to 1st base. The rule book states that other than the initial play on a batted ball, any defensive player that impedes the progress of a runner or batter/runner has committed obstruction.

But, during one of our clinics the instructors just told everyone that if a throw pulls F3 into the path of the batter/runner, you have nothing but a train wreck because both players were doing what they were suppose to do. So what is the correct answer on the test?