Sachdev finds two metal bars and decides that since they are stuck together, at least one of metal bars must be a magnet. Sachdev pulls the bars apart and uses a marker to label each end of the bars. She lays bar CD on the table and then ties a string around bar AB and hangs end A above end D, as shown in the diagram. Sachdev finds that the end marked A tips downward until it is touching the end marked D. Which test allows Sachdev to draw a conclusion about the magnetic properties of each metal bar? Choose the correct answer. She hangs A directly above C and sees that the two ends attract. She concludes that both bar AB and bar CD always produce magnetic fields. She hangs B directly above C and sees that the two ends attract. She concludes that both bar AB and bar CD always produce magnetic fields. She hangs B directly above C and sees that the two ends attract. She concludes that bar CD always produces a magnetic field, but bar AB only temporarily produces a magnetic field. She hangs A above the center of bar CD and finds that A is only weakly attracted to CD. She concludes that bar CD always produces a magnetic field, but bar AB only temporarily produces a magnetic field.