For a successful operation of a thermonuclear reactor, Lawson's criterion is given by

Correct Answer: (D) n$\tau$ T >= 150 * 10^20 keVs/m^3

Lawson's criterion specifies the minimum confinement product of plasma density (n), energy confinement time (tau), and temperature (T) required for net energy-producing thermonuclear fusion, which is approximately n*tau*T >= 150 * 10^20 keVs/m^3 for D-T fusion.