Explanation

This uses the rhombus diagonal property: the diagonals bisect each other at right angles. Half of the given diagonal is 5 cm, so the other half-diagonal is √(13² - 5²) = 12 cm, making the full second diagonal 24 cm. Area = (d₁d₂)/2 = (10 × 24)/2 = 120 cm². Option (a) 140 is the trap from miscomputing the second diagonal. Hence option (c).