Final answer:
Decreasing resistance in one branch of a parallel circuit increases the total current because it provides another path for electricity, reducing the overall resistance.
Step-by-step explanation:
With a constant supply voltage, when the resistance is decreased in any one branch of a parallel circuit, it results in an increase of the total current in the circuit. This is because adding resistors in parallel provides another path for the current, effectively decreasing the overall resistance of the circuit. It's important to understand that in parallel circuits, the voltage across each branch is the same but the current flowing through each branch may differ based on the resistance of each branch. Furthermore, when resistance is decreased in a parallel branch, according to Ohm's law (V = IR), more current will flow through that branch, thereby increasing the total current flowing through the circuit.