Answer 2

2.  Choice B is the correct answer.  There are no p waves seen in this rhythm strip so choice A and C are incorrect.  With First Degree AV Block the PR interval is just length and there is no dropping of the QRS complex.  Junctional bradycardia has inverted P waves occurring before, during or immediately after the QRS complex.  Presumably, since there is no P waves seen they are within the QRS complex. The pacemaker is coming from the AV junction, which has an inherent rate of 40-60.  Faster then 60 is referred to as junctional tachycardia, slower than 40 is referred to a junctional bradycardia.  Atrial fibrillation does not have any discernible P waves but the rhythm is too slow for that.  In addition, it is an irregularly, irregular rhythm and this rhythm strip is regular.