Unlike a test that directly measures blood alcohol content (BAC), a Preliminary type your answer... Test (PBT) measures the amount of alcohol in your __ type your answer...

## Step 1<br />The problem is asking for the substance that a Preliminary Breath Test (PBT) measures in the human body. The PBT is a type of test that is used to estimate the amount of alcohol in a person's system. <br /><br />## Step 2<br />The PBT measures the concentration of alcohol in the breath. This is done by having the person blow into a device that measures the alcohol content in the breath. <br /><br />## Step 3<br />The concentration of alcohol in the breath is then used to estimate the blood alcohol content (BAC). The BAC is a measure of the amount of alcohol in a person's bloodstream.