The correct answer is: C. non-directional.
An admittance relay is a type of relay that measures the current and voltage flowing through a circuit and compares it to a set of predetermined values. If the current and voltage are within the predetermined values, the relay will not operate. However, if the current and voltage are outside of the predetermined values, the relay will operate.
An impedance relay is a type of relay that measures the impedance of a circuit. The impedance of a circuit is the opposition to the flow of current. An impedance relay will operate if the impedance of a circuit is outside of a predetermined value.
A directional relay is a type of relay that measures the direction of current flow in a circuit. A directional relay will operate if the current is flowing in a predetermined direction.
A non-directional relay is a type of relay that does not measure the direction of current flow in a circuit. A non-directional relay will operate regardless of the direction of current flow.
In conclusion, an admittance relay is a non-directional relay because it does not measure the direction of current flow in a circuit.