The correct option is C III only
From II, let l=4x,b=6x and h=5x
Then, area of the hall =(24x2)m2.
From I. Area of the hall =24m2
From II and I, we get 24x2=24⇔x=1
∴l=4m,b=6andh=5m$.
Thus, area of two adjacent walls =[(l×h)+(b×h)]m2 can be found out and so the cost of painting two adjacent walls may be found out.
Thus, III is redundant.
∴ Correct answer is (C)