A food item gives a blue-black color with iodine. What does this tell you about the composition of this food item?

Explanation

### Step-by-Step Solution:

1. **Understanding the Reaction**: When iodine is added to a food item, a color change can occur. In this case, the food item gives a blue-black color.

2. **Identifying the Color Change**: The blue-black color is a specific indicator that suggests the presence of certain carbohydrates in the food item.

3. **Recognizing the Substance**: The blue-black color is primarily associated with the presence of starch. When iodine interacts with starch, it forms a complex that results in this characteristic color change.

...