Explanation:

Let the heights of these towers be represented by P,S,U,I,C. Pearl Towers is taller than Sky Towers but shorter than Unity Towers, => U > P > S Unity Towers and Cyber Towers are of same height, => C = U > P > S Pearl Towers is shorter than Indus Towers, => I is either the tallest or the second tallest building. Thus, Pearl towers is the second shortest.