Final answer:
Trade disputes are a political cause of instability in international markets; they lead to tariffs and import quotas that impact trade flows and prices.
Step-by-step explanation:
Among the options provided, trade disputes is a political cause of instability in international markets. Trade disputes between countries can lead to the imposition of tariffs and import quotas, which alter the conditions for international trade and can result in retaliatory measures. This impacts global trade flows by changing import and export prices. In contrast to the other options given, trade disputes are a direct source of political instability affecting international markets, as opposed to factors like varied taxing conventions or differences in economic philosophies, which are underlying structural elements of economies. It's essential to recognize that varying exchange rates can also disturb trade flows, impacting import and export prices and thus affecting countries' economies.