Kirchhoff’s loop rule for circuit analysis is an expression of?

Conservation of energy

Explanation:

Gustav Kirchhoff, a German physicist proposed a rule called Kirchhoff's loop rule also known as Kirchhoff's second rule which states that for any closed loop, the potential difference including the voltage supply is zero. That means energy supplied by a voltage source must absorbed for balance by other components in the loop

This fulfils the law of conservation of energy

continuous conducting path for current, power supply