Concept:For a capacitor, the charge stored is directly proportional to the potential difference across it.Explanation:The relation is Q=CV.Here, C is the capacitance.For a fixed capacitor, C remains constant.So, as V increases, Q increases linearly.When V=0, the charge Q is also 0.Therefore, the graph of Q against V must be a straight line passing through the origin.Answer:The correct graph is the straight line through the origin.