The diagram below shows a simple electrical circuit.

Which of the following would always increase the flow of current through the lights in the circuit shown above?

a
Decreasing the battery voltage and increasing the resistance of the lights.
b
Increasing the battery voltage and increasing the resistance of the lights.
c
Decreasing the battery voltage and decreasing the resistance of the lights.
d
Increasing the battery voltage and decreasing the resistance of the lights.

d. Increasing the battery voltage and decreasing the resistance of the lights.