Which aspect is a key characteristic of foreign exchange markets?

The correct choice highlights that foreign exchange markets operate as a global telecommunications network primarily among large commercial banks. This characteristic is crucial because the foreign exchange market is decentralized and not conducted on a physical exchange; instead, it functions over-the-counter (OTC) through a network that facilitates trading among banks, financial institutions, businesses, and individuals across different time zones. This extensive network enables participants to exchange currencies continuously, which is essential for international trade and investments.

Given this understanding, the foreign exchange market's reliance on advanced telecommunications technology allows for high liquidity and the ability to operate 24/5 without interruptions. Such a system is vital for managing currency risks and facilitating transactions that involve multiple currencies, accommodating the vast and diverse transactions occurring globally.

The other options present narrower or incorrect definitions that do not encompass the comprehensive and dynamic nature of the foreign exchange markets. They do not effectively convey how currencies are traded on a global scale or who the primary participants are.