A portion of embankment having a uniform up gradient of 1 in 500 is circular with a radius of 1000 m of the centre line. It subtends 180° at the centre. If the height of the embankment is 1 m at the lower end and side slope is 2 : 1, the earth work involved is
A26,000 m^3
B26,500 m^3
C27,000 m^3
D27,500 m^3