For Apple's products, it has a number of an exclusive long-term strategic partnerships with its key suppliers to help produce the products that Apple needs. Apple has also diversified its supply chain operations to contain new manufacturing partners in Tiawan and China and Apple tends to negotiate favorable pricing terms and conditions, acquire to strategic raw materials and assurance high production volumes with its suppliers for complete dedication to build Apple products. Therefore, based on the above Apple Inc. strategy and resources, when should they consider building internally, and when should they consider buying from a supplier? Thank you.