Step 1:Check HDI value of Congo.
From the table, Congo has an HDI of 0.593.
Step 2:Match with HDI categories.
- 0.800+ → Very High
- 0.700--0.799 → High
- 0.550--0.699 → Medium
- Below 0.550 → Low
Step 3:Conclusion.
Since 0.593 lies in the range 0.550--0.699, Congo falls under Medium human development.
\[
\boxed{(C)\ \text{Medium}}
\]