First-degree heart block is characterized by
a. prolonged pr interval.
b. absent p waves.
c. variable pr interval.
d. widened qrs complex.

The answer is A. Prolonged PR interval.

Explanation:

First-degree heart block is characterized by prolonged PR interval. First-degree A-V blockages occur when electrical impulses that move through the atrioventricular node are delayed, but not obstructed. It presents with a slow conduction and without lost beats.

it would lead to upper respiratory infections and pneumonia.

the most common energy conversion is from kinetic energy to potential energy, and then from potential energy to kinetic energy.

later on comes the heat energy, mechanical energy, and other energy conversions.

this energy conversion is so common that we can find it in our day to day lives as well.

- one of the most common energy conversions involves the changing of potential energy to kinetic energy or kinetic energy to potential energy