Questions: If the sinuatrial (SA) node is damaged, the heart will likely beat at bpm. Multiple Choice 21 70 to 80 20 to 40 10 to 20 0 to 10 40 to 50

The answer is: 20 to 40 bpm.

Explanation for each option:

1. 21 bpm: This is not a typical heart rate for any of the heart's pacemakers.
2. 70 to 80 bpm: This is the normal heart rate range when the SA node is functioning properly.
3. 20 to 40 bpm: This is the typical heart rate range when the atrioventricular (AV) node takes over as the pacemaker in the absence of a functioning SA node.
4. 10 to 20 bpm: This is too low for the AV node or any other pacemaker in the heart.
5. 0 to 10 bpm: This is not a viable heart rate for sustaining life.
6. 40 to 50 bpm: This is slightly higher than the typical rate for the AV node but could be seen in some cases where the AV node is compensating.

Summary: If the SA node is damaged, the heart will likely beat at 20 to 40 bpm, as the AV node takes over the pacemaking function.