Which of the following countries can be considered highly developed based on the human development index (HDI)?
A. Country B: 0.64
B. Country D: 0.75
C. Country C: 0.39
D. Country A: 0.91
A. Country B: 0.64
B. Country D: 0.75
C. Country C: 0.39
D. Country A: 0.91