Concept:The reaction force of water escaping from a hole is the rate of change of momentum, and for two opposite holes the resultant is the difference of the two forces.Explanation:Let the depths of the two holes below the water surface be h1 and h2.Since the vessel is wide, the efflux speed at depth h is given by Torricelli’s theorem:v=2ghThe reaction force for one hole is:F=ρAv2Substituting v2=2gh, we get:F=ρA(2gh)=2ρAghThus, forces on the two holes are:F1=2ρAgh1,F2=2ρAgh2The holes are on opposite sides, so the forces act in opposite directions.Therefore, the resultant force is:Fresultant=F2−F1=2ρAg(h2−h1)Given the height difference between the holes is x, i.e. h2−h1=x, we get:Fresultant=2ρAgxAnswer:2ρAgxOption B.