The correct answer is (d) 360°
Explanation: As we know that the external angles for a supplementary pair of angles with the internal angles. We take any square of any length, as we know that all the angles of a square measure 90° and we also know that they are supplementary.
Therefore 90°+x = 180°
Therefore x = 90°
Similarly the other three external angles also measure the same. Therefore the sum total of all the external angles is 360°.