If, in any given plane, one end of the column is unrestrained, Its unsupported length ‘l’ shall not exceed ______. Where ‘b’ is width and ‘D’ is depth of cross-section in plane under consideration.

• A. \(\frac{{100b}}{D}\)
• B. \(\frac{{100{b^2}}}{D}\)
• C. \(\frac{{100D}}{b}\)
• D. \(\frac{{100{D^2}}}{b}\)