Final answer:
The length of the diameter of a circle with a radius of 4 cm is 8 cm.
Step-by-step explanation:
To find the length of the diameter of a circle, you simply double the radius. In this case, the radius is 4 cm, so the diameter would be 2 times 4 cm, which is 8 cm. Therefore, the correct answer is c. 8cm.
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