What indicates bradycardia for an infant?

Bradycardia in infants is defined as a heart rate that is slower than what is considered normal for their age. Typically, the normal resting heart rate for infants ranges from about 120 to 160 beats per minute. Therefore, a heart rate significantly below this threshold would indicate bradycardia.

In this context, the correct answer reflects a heart rate that falls under the bradycardia range. A heart rate of 100 BPM is lower than the standard normal range for infants, indicating a potential risk for bradycardia. Conversely, heart rates above this threshold, such as 105 BPM, 95 BPM, and 80 BPM, would either indicate normal or elevated heart rates for infants, depending on the specific values. Since 100 BPM is on the cusp of the normal range but still below it, it is the best indicator of bradycardia among the choices given.