Final answer:
The intermediary involved in e-commerce is online marketplaces, which connect buyers and sellers on a global scale for both consumer and business transactions.
Step-by-step explanation:
In e-commerce, the type of intermediary involved is d) Online marketplaces. These platforms serve as digital intermediaries that connect buyers and sellers from around the world, breaking down the traditional boundaries of local markets. Online marketplaces like Amazon, eBay, and Alibaba have grown significantly due to advancements in technology and the effects of globalization. They facilitate both consumer-to-consumer and business-to-business transactions, making it easier for consumers to purchase goods from different firms in the goods market and firms to source supplies potentially from all over the globe.