To find the area of a circle, you can use the formula:
\[ \text{Area} = \pi r^2 \]
where \( r \) is the radius of the circle. The radius is half of the diameter. Given that the diameter is 10 millimeters:
\[ r = \frac{10 \text{ mm}}{2} = 5 \text{ mm} \]
Now, substituting the radius into the area formula using \( \pi \approx 3.14 \):
\[ \text{Area} = 3.14 \times (5 \text{ mm})^2 \]
Calculating \( (5 \text{ mm})^2 \):
\[ (5 \text{ mm})^2 = 25 \text{ mm}^2 \]
Now, substitute this back into the area formula:
\[ \text{Area} = 3.14 \times 25 \text{ mm}^2 \]
Calculating this:
\[ 3.14 \times 25 = 78.5 \text{ mm}^2 \]
Thus, the area of the circle is 78.5 square mm.
So, the correct response is:
78.5 square mm