Final answer:
The correct relationship between the diameter and circumference of a circle is that the circumference is about three times the diameter.
Step-by-step explanation:
The relationship between the diameter and the circumference of a circle is given by the formula C = πd, where C represents the circumference and d represents the diameter. Since π (pi) is approximately 3.14159, for any circle, the circumference is slightly more than three times the diameter. The correct choice for the relationship between diameter and circumference is that circumference is about 3x the diameter. Therefore, the correct answer in this case would be 'D. Circumference is about 3x the diameter.'