Final answer:
The Emissions Trading System (ETS) is a market-oriented environmental policy. It aims to reduce greenhouse gas emissions through the buying and selling of permits. The EU ETS is a well-known example of this system.
Step-by-step explanation:
Emissions Trading System (ETS) is a market-oriented environmental policy that falls under the subject of Social Studies. It is designed to reduce greenhouse gas emissions by allowing countries or companies to buy and sell permits, also known as allowances, to emit a certain amount of these gases.
The EU ETS is the largest and most well-known example of an ETS, which covers various sectors in European countries. The challenges associated with ETS include environmental concerns, economic implications, educational needs, and emotional reactions from stakeholders.