A U tube with both ends open to the atmosphere,is partially filled with water. Oil, which is immiscible with water, is poured into one side until it stands at a distance of 10mm above the water level on the other side. Meanwhile the water rises by 65 mm from its original level (see diagram). The density of the oil is 

(a) $650$ $kg$ $m^{-3}$

(b) $425$ $kg$ $m^{-3}$

(c) $800$ $kg$ $m^{-3}$

(d) $928$ $kg$ $m^{-3}$