The correct answer is D. H - L.

Explanation:
- Range: The range is calculated as the difference between the highest value (H) and the lowest value (L) in a data set. The formula is \( \text{Range} = H - L \). This gives a measure of the spread or dispersion of the data.

- A. H + L: This would add the highest and lowest values, which does not give the range.

- B. L x H: This represents the product of the highest and lowest values, not the range.

- C. L - H: This is the difference in the opposite order and would give a negative value if H is greater than L.

So, the correct formula for range is \( H - L \).