As per IS 456-2000, the unsupported length (l) of a column whose one end is unrestrained in any given plane shall not exceed (Given: b = width of the column cross-section and D = depth of the cross-section measured in the plane under consideration)

Options

A) 60b or 450D

B) 45b or 300D

C) 30b or 200D

D) 15b or 100D

As per clause 25.1.1 of IS 456-2000, the unsupported length (l) of a column whose one end is unrestrained in any given plane shall not exceed the smaller of 30b or 200D, where b is the width and D is the depth of the column cross-section.

Therefore, option C is the correct answer.