Answer :

A normal fasting blood glucose level is an important indicator of metabolic health. To determine what constitutes a normal fasting blood glucose level, we should consider various ranges provided in the options:

- Option A: 10-30 mg/dL
- Option B: below 100 mg/dL
- Option C: 110-150 mg/dL
- Option D: above 100 mg/dL

A fasting blood glucose level that's too low (for example, 10-30 mg/dL) can be indicative of hypoglycemia, which is not normal and can be harmful.

On the other hand, fasting blood glucose levels between 110-150 mg/dL or above 100 mg/dL suggest hyperglycemia, possibly indicating prediabetes or diabetes.

A level that is considered within the normal range is below 100 mg/dL, as higher levels, specifically over 100, are not considered normal and typically indicate a potential health issue.

Thus, the correct answer to the question is:

Option B: below 100 mg/dL