A mould has a down sprue whose length is 20 cm and the cross sectional area at the base of the down sprue is 1 cm2. The down sprue feeds a horizontal runner leading into the mould cavity of volume 1000 cm3. The time required to fill the mould cavity will be
(a) 4.05 s(b) 5.05 s
(c) 6.05 s (d) 7.25 s