The sleep stage when heart rate rises and breathing becomes rapid and irregular is A Stage 1 B REM C Stage 3 D Stage 2

## Step 1<br />The problem is asking us to identify the sleep stage where the heart rate rises and breathing becomes rapid and irregular. The options provided are different stages of sleep.<br /><br />## Step 2<br />The Rapid Eye Movement (REM) stage of sleep is characterized by rapid and irregular breathing and an increased heart rate. This is the stage where most dreaming occurs.<br /><br />## Step 3<br />The other stages of sleep, namely Stage 1, Stage 2, and Stage 3, do not exhibit these characteristics. Therefore, the correct answer is B, REM.