Pick up the correct statement from the following :

• The maximum rate of storm run off is called peak drainage discharge
• Rational method of estimating peak run off, may be used precisely for areas less than 50 hectares
• The period after which the entire area starts contributing to the run off, is called the time of concentration
• The time required by water to reach the outlet of a catchment from the most remote point, is called time of concentration
• All the above.