$${\rm I}.\,\,\,\,$$ Effective length of a battened column is usually increased to account for the additional load on battens due to the lateral expansion of columns.
$${\rm II}.\,\,\,\,$$ As per $$IS:$$ $$800$$-$$1984,$$ permissible stress in bending compression depends on both Euler buckling stress and the yield stress of steel.
$${\rm III}.\,\,\,\,$$ As per $$IS:$$ $$800$$-$$1984,$$ the effective length of a column effectively held in position at both ends but not restrained against rotation, is taken to be greater than that in the ideal end conditions.
The TRUE statements are
$${\rm I}.\,\,\,\,\,\,\,\,\,$$ The entire cross-sectional area of the connected leg is assumed to contribute to the effective area in case of angles.
$${\rm II}.\,\,\,\,\,\,\,\,\,$$ Two angles back-to-back and tack-welded as per code requirements may be assumed to be behave as a $$T$$-section
$${\rm III}.\,\,\,\,\,\,\,\,\,$$ A check on slenderness ratio may be necessary in some cases.
The TRUE statements are
Where $$\alpha $$ is equal to
The reaction at $$C$$ is