Explanation:

Recently, a fire broke out at Natanz, an Underground Nuclear Facility of Iran used for enriching uranium. Located in Iran’s central Isfahan province in Tehran, Natanz hosts the country’s main uranium enrichment facility. It is known as the first Pilot Fuel Enrichment Plant of Iran. It is among the sites monitored by the International Atomic Energy Agency (IAEA) after Iran’s 2015 nuclear deal. Hence option 3rd is correct.