Final answer:
The emir of Kuwait returned after exile post Operation Desert Storm in the 1990s, specifically after the Gulf War ended with the defeat of Iraqi forces in 1991. The emir of Kuwait returns after 7 months in exile in the 1990s.
Step-by-step explanation:
The emir of Kuwait returned after 7 months in exile following Operation Desert Storm which began on January 16, 1991. This operation was part of the Gulf War, where a UN coalition led by the United States took military action to expel Iraqi forces from Kuwait. After 45 days of fighting, Iraqi forces were defeated and the military was ousted from Kuwait. Hence, the correct answer to the student's question is (d) 1990s.