Which sequence correctly lists the main spectral classes from hottest to coolest?

Answer

O, B, A, F, G, K, M

The established spectral type sequence in descending order of temperature is O, B, A, F, G, K, M, making O-type the hottest and M-type the coolest.

Which sequence correctly lists the main spectral classes from hottest to coolest?
physicsclassificationastronomytemperaturestars