The most probable kinetic energy of a gas molecule at TK is:

According to Maxwell speed distribution of molecules of gas at temperature , most probable speed $\Rightarrow$ $U=\sqrt{\frac{2KT}{m}}$

So, the corresponding energy is:  $E=KT$

According to the Maxwell Boltzmann energy distribution, most probable kinetic energy:

$E_k=\frac{kT}{2}$

So, option A is correct answer.