Blood alcohol concentration can be determined by a breath test because A there is always a tiny bit of blood in saliva. about five percent of the alcohol leaves the body unchanged in the breath pers C it is more accurate than blood. c D . it metabolized alcohol differently

## Step 1<br />The problem is asking us to identify the correct reason why blood alcohol concentration can be determined by a breath test. The options provided are:<br />A. There is always a tiny bit of blood in saliva.<br />B. About five percent of the alcohol leaves the body unchanged in the breath.<br />C. It is more accurate than blood.<br />D. It metabolizes alcohol differently.<br /><br />## Step 2<br />We need to evaluate each option based on its scientific accuracy.<br /><br />## Step 3<br />Option A is incorrect because while there is some blood in saliva, it is not enough to measure alcohol concentration accurately.<br /><br />## Step 4<br />Option B is correct. When a person consumes alcohol, a small percentage of it is excreted unchanged in the breath. This is the basis for breathalyzers.<br /><br />## Step 5<br />Option C is incorrect. The accuracy of a breath test versus a blood test depends on the context and the specific test being used. It's not a general rule that breath tests are more accurate.<br /><br />## Step 6<br />Option D is incorrect. The way the body metabolizes alcohol is not directly related to the ability to measure its concentration in breath.