The correct answer is: C. 6%
The maximum reinforcement in a column is 6% of the gross cross-sectional area of the column. This is to ensure that the column has sufficient strength to carry the loads imposed on it.
Option A: 2% is too low and may not be sufficient to carry the loads imposed on the column.
Option B: 4% is a common value for the maximum reinforcement in a column. However, it may not be sufficient for columns that are subjected to high loads.
Option D: 8% is too high and may lead to cracking of the column.
It is important to note that the maximum reinforcement in a column may vary depending on the type of column, the loads imposed on the column, and the materials used to construct the column. It is always advisable to consult a structural engineer to determine the appropriate maximum reinforcement for a particular column.