How is this represented in Magento?

You are working on a jewelry store that sells rings. Each ring allows an adjustment in size. The customer specifies finger size in inches and the merchant physically adjusts the stocked ring to the required size.

How is this represented in Magento?
A . Using custom options, with rings as simple products
B . Using categories, with each ring size as a separate product
C . Using configurable products, with ring size as an attributive value
D . Using custom options, with rings as bundle products

Answer: C