The correct option is B inversely
If the number of pipes used to fill a drum is increased, the volume of water flowing to the drum in unit time will be more. Since the volume to be filled is constant, and the volume flow rate increases, the time taken to fill the drum decreases.
Now, flow rate x time = constant
Hence, we can say that the number of pipes used to fill the drum is inversely proportional to the time taken to fill the drum.