Ricky Is an Online Golf Equipment Merchant Who Just Created

Ricky is an online golf equipment merchant who just created a new Google Merchant Center account. When Ricky creates his first data feed, he must add unique product identifiers for his products. Which combination of 'gtin', 'mpn' and 'brand' is valid?

A) Both 'gtin' and 'mpn' must be includeD
B) Two identifiers from 'gtin', 'mpn' and 'brand' must be used
C) Only 'brand' is required
D) Only 'mpn' is required