Answer:
D. Use 3.14159 for π.
Explanation:
Given a circle with diameter, d, the circumference is calculated using the formula:

Given that d = 1220 millimeters.
When π = 3.14

When π = 3.14159

Therefore, for Frank to improve the accuracy of measurement of the circumference, he can use 3.14159 for π.
Option D is correct.