ANS:B - 15

A column is regarded as a "long column" when its effective length-to-lateral dimension ratio exceeds a certain threshold. This ratio is an important parameter in determining the behavior and stability of columns under compressive loads. The effective length (L_e) of a column refers to the distance between the points of inflection where the column is effectively prevented from rotating or moving laterally. The lateral dimension typically refers to the minimum cross-sectional dimension of the column, such as its diameter in the case of a circular column or its least width or thickness in the case of a rectangular or square column. The threshold ratio beyond which a column is considered "long" depends on various factors, including the material properties, end conditions, and loading conditions. However, a commonly used criterion is that a column is considered long when its effective length-to-lateral dimension ratio exceeds 12. Therefore, none of the provided options match this commonly used criterion. However, if we consider the closest option, it would be: 15 This implies that if the effective length of a column is more than 30 times its lateral dimension, it is typically considered a long column.