Why was South-Korea, between 1960s and 1980s called as "miracle on the Han River"

It rapidly developed into an Economic power

The correct answer is Option 1 - It rapidly developed into an Economic power

The term "Miracle on the Han River" signifies the Economic aspect of South Korea's development.

The Korean peninsula was divided into South Korea (The Republic of Korea) and North Korea (Democratic People’s Republic of Korea) at the end of the Second World War along the 38th Parallel. The Korean War during 1950 - 53 and the dynamics of the Cold War era further intensified the rivalries between the two sides. Both the Koreans finally became members of the UN on 17 September 1991.
Meanwhile, South Korea emerged as a centre of power in Asia. Between the 1960s and the 1980s, it rapidly developed into an economic power, which is termed the “Miracle on the Han River”. Signalling its all-around development, South Korea became a Member of the OECD in 1996. In 2017, its economy is the eleventh largest in the world and its military expenditure is the tenth largest