Pick up the correct statement from the following:

• The basic length of a runway is increased at a rate of 7% per 300 m of elevation of M.S.L.
• The standard temperature at the site is obtained by reducing the standard sea level temperature of 15°C at the rate of 6.5°C per 1000 m rise in elevation
• The aerodrome reference temperature is the monthly mean of the mean daily temperature for the hottest month of the year
• All the above.