Final answer:
Atrial flutter occurs when the atrial rate is D) between 250 and 350. It is a rapid rate that can cause palpitations and shortness of breath, differing from normal sinus rhythm and bradycardia.
Step-by-step explanation:
Atrial flutter is a type of cardiac arrhythmia characterized by rapid and regular atrial contractions. The correct answer to the student’s question is D) between 250 and 350. In atrial flutter, the atria of the heart beat very rapidly, at a rate significantly faster than the normal. This rapid rate can lead to symptoms such as palpitations, shortness of breath, and fatigue. It is distinct from normal sinus rhythm, where the resting heart rate falls between 60 and 100 beats per minute, and from bradycardia, which is a slower than normal heart rate (< 60 beats per minute).