The correct option is C Upper limit of rainfall, which is justified climatologically
The Probable Maximum Precipitation(PMP) may be defined as the maximum depth of precipitation for a given duration that may possibly occur on a given catchment at any time of the year. Hence such a precipitation would result from the possible severe most storm that may result from the worst possible combinations of hydrological conditions in the area.
Probable Maximum Flood (PMF) is the extreme flood that is physically possible in a region as a result of severe most combinations, including rare combinations of meteorological and hydrological factors. The PMF is used in situations where the failure of the structure would result in loss of life and catastrophic damage and as such complete security from potential floods is sought.