Final answer:
The answer is (a) True, as the value chain includes both upstream and downstream portions of the supply chain, illustrated by the global production process for items like the iPhone.
Step-by-step explanation:
The term 'value chain' does indeed encompass both upstream and downstream portions of the supply chain, making the answer to the initial question (a) True. Upstream activities involve sourcing materials, while downstream activities include distribution and marketing. The value chain's partitioning enables specialization and efficiency in production, as parts of a product can be made in different locations, leading to economic gains through intra-industry trade. The production of the iPhone, for example, is an illustration of this: design and engineering in the U.S., parts supplied from Korea, assembly in China, and marketing again in the U.S.