Concept:Instruments are connected according to the quantity they measure.Explanation:A voltmeter measures potential difference between two points.So it must be connected in parallel across the component to read the same voltage.An ammeter measures current and is connected in series.A galvanometer detects small current and is connected in series.An ohmmeter measures resistance and is used without being connected in the live circuit.Therefore, the instrument connected in parallel across a resistor is the voltmeter.Answer:B. Voltmeter