How can I represent a schematic diagram of circuit for three D-cells placed in a battery pack to power a circuit containing three light bulbs in series?
Even though it is not given in the problem, all cells should be connected in series.
It is a good practice to connect a switch in series in the circuit always.
It is a safety feature.
Your circuit looks like this:
It is also not given if you are using Normal cells of 1.5 V each type
or Rechargeable cells of 1.25 V each. If you know then appropriately mention the voltage of the battery pack.
It is recommended not to attempt mix and match of different types of cells. Use all three of the same kind.
Sorry for being late.