We use Wien's displacement law, which states that the wavelength \( \lambda_m \) corresponding to the maximum energy of the radiation is inversely proportional to the temperature:
\[
\lambda_m T = \text{constant}
\]
Given that the wavelength of radiation corresponding to maximum energy is \( \frac{\lambda_m}{3} \), we can set up the equation:
\[
\frac{\lambda_m}{3} \times T_2 = \lambda_m \times T
\]
Simplifying:
\[
\frac{T_2}{3} = T
\]
\[
T_2 = 3T
\]
Thus, the temperature \( T_2 \) is three times the original temperature \( T \), making the correct answer \( 3T \).