Argon is a monatomic gas, so all supplied heat at constant volume goes to translational degrees of freedom (100%) and none to rotational (0%).

The triple point of water is commonly given ≈273.16 K; the closest provided option is 273.15 K as the intended choice.

Heating increases the internal energy (microscopic kinetic and potential energies) of the substance.

Thomas Johann Seebeck discovered the thermoelectric (Seebeck) effect, so Seebeck is the correct inventor.

Normal human body temperature is about 36.9–37.0 ℃, so 36.9 ℃ is the correct choice.

Max Planck developed the theoretical explanation of the blackbody spectrum, introducing quantized energy elements.

For ideal gases γ = (f+2)/f and for monatomic gas (f=3) γ = 5/3, which is the maximum value for classical ideal gases.

The kinetic energy ½m u² supplies the heat to raise temperature mcΔT and the latent heat mL, so ½m u² = mc(475−25) + mL.

Average molar C_v = (1.5R + 3R)/2 = 2.25R, C_p = C_v + R = 3.25R, so γ = C_p/C_v = 3.25/2.25 ≈ 1.444 ≈ 1.44.

Overall efficiency is product of efficiencies: 0.90×0.60 = 0.54 → 54% (option C).