Keeping maintainability in mind, how do you build this into Magento?

You are building an tool that imports products from an ERP. There are 20 columns of additional information that are associated with each product. This extra information must also be associated with an update time to know when to refresh the data.

Keeping maintainability in mind, how do you build this into Magento?
A . Utilize an extension attribute.
B . Override the Product model and add the fields.
C . Create a separate model and build code to associate the two record types.
D . Create 20 EAV attributes and check their updated_at column.

Answer: A