The correct answer is: A) Investment in social sectors.
Kerala’s high HDI is attributed to its focus on investment in social sectors such as education, healthcare, and social welfare. This has resulted in a high level of human development, with Kerala having a high life expectancy, low infant mortality rate, and high literacy rate.
Heavy industrialization, rapid economic growth, and large-scale infrastructure projects are not the main reasons for Kerala’s high HDI. While these factors have contributed to Kerala’s economic development, they have not had a significant impact on human development.
Kerala’s focus on investment in social sectors has been a key factor in its success. This has resulted in a high level of human development, which is reflected in Kerala’s high HDI.