Concept: Post-disaster assessment is done after a disaster to evaluate damage, affected people, loss of property, impact on infrastructure, and recovery needs.
Step 1: Understand flood post-disaster assessment.
After a flood, authorities assess the affected population, damaged houses, damaged crops, infrastructure loss, and economic damage.
\[
\text{Post-flood assessment} = \text{Damage + Loss + Need assessment}
\]
Step 2: Check the given activities.
Identifying affected population is done because relief and rehabilitation depend on it.
Mapping inundation extent is done to know the flooded area.
Estimating economic damage is also done to calculate financial loss.
Step 3: Identify what is not part of post-disaster assessment.
Private enterprises develop is not a direct post-disaster flood assessment activity. It may be related to development or economy, but it is not a standard assessment task after floods.
Therefore, the correct answer is C Only.