According to Euler's column theory, the crippling load of a column is given by $${\text{p}} = \frac{{{\pi ^2}{\text{E}}I}}{{{\text{C}}{l^2}}}.$$   In the Euler's formula, the value of C for a column with one end fixed and the other end free, is

A. $$\frac{1}{2}$$

B. 1

C. 2

D. 4

Answer: Option D