KVL stands for Kirchhoff's Voltage Law, which is a fundamental principle in electrical circuit analysis. It is based on the principle of conservation of energy and is used to determine the voltages across different elements in a circuit.

KVL applies to both mesh analysis and nodal analysis, making option (c) "Both mesh and nodal" the correct answer.

Explanation:

1. KVL in Mesh Analysis:
- Mesh analysis is a method used to analyze circuits with multiple loops.
- In this method, the circuit is divided into meshes or loops, and KVL is applied to each mesh separately.
- KVL states that the sum of voltage drops around any closed loop in a circuit is equal to the sum of voltage rises.
- By applying KVL to each mesh, a set of equations can be obtained that relate the voltage drops across the elements in the circuit.
- These equations can then be solved simultaneously to determine the unknown currents in the circuit.

2. KVL in Nodal Analysis:
- Nodal analysis is a method used to analyze circuits with multiple nodes.
- In this method, the circuit is divided into nodes, and KVL is applied to each node separately.
- KVL states that the sum of currents entering a node is equal to the sum of currents leaving the node.
- By applying KVL to each node, a set of equations can be obtained that relate the currents at different nodes in the circuit.
- These equations can then be solved simultaneously to determine the unknown node voltages in the circuit.

3. Importance of KVL:
- KVL is a fundamental principle in circuit analysis and is used to determine the voltages across different elements in a circuit.
- It is based on the principle of conservation of energy, which states that the total energy in a closed system remains constant.
- By applying KVL, we can ensure that the energy flow in a circuit is conserved and the circuit obeys the laws of physics.
- KVL is essential in determining the voltage drops across resistors, capacitors, inductors, and other circuit elements, which are crucial for designing and analyzing electrical circuits.

In conclusion, KVL is applied in both mesh analysis and nodal analysis, making option (c) "Both mesh and nodal" the correct answer. It is a fundamental principle in circuit analysis that ensures the conservation of energy in electrical circuits.