The passage focuses on how established structures and institutions in developed markets provide a historical context and reference to management, thereby making the process of management easier. In contrast, the absence of some or all of these structures becomes the biggest challenge for management in developing markets. Thus the most obvious conclusion from the passage is that the biggest difference between these two types of markets is that developing markets are unable to provide the structures of a developed market. Hence, option (C) is valid.

Option (A) is invalid because it claims that historicals are irrelevant to emerging markets, whereas they are relevant but often unavailable.

Due to the absence of structures and institutions, buyers and sellers may not be able to transact optimally in a developing market. Also, the transactional costs and operational challenges may increase. However, all these are inferences and not conclusions. Hence, options (B) and (D) are invalid.

Hence, the correct answer is option (C).