Final answer:
The stellar spectral types classify stars by temperature from hottest to coolest as O, B, A, F, G, K, M, with O being the hottest and M being the coolest. Additional classes L, T, and Y indicate even cooler objects. Our Sun is a G-type star, which is cooler than O-type stars but hotter than M-type stars.
Step-by-step explanation:
The stellar spectral types are a classification system for stars based on their surface temperatures, which are reflected in the characteristics of their spectra. The primary spectral classes are O, B, A, F, G, K, and M, which are listed in order from hottest to coolest. There are also three additional classes, L, T, and Y, used for cooler star-like objects, such as brown dwarfs.
O-type stars are the hottest, with surface temperatures that can exceed 30,000K. At the other end of the spectrum, M-type stars are relatively cool, with surface temperatures as low as 2,000K – 3,500K. Furthermore, each spectral class is divided into ten subclasses, ranked by numbers 0 through 9, with 0 being hotter and 9 being cooler within that class.
For context, our own Sun is classified as a G2 type star, which means it is cooler than O and B stars but hotter than K and M stars. Thus, the correct answer to the student's question is a) O, B, A, F, G, K, M. O-type stars are hot, M-type stars are cool.