Tough question, as I recall. Convection occurs in the convection zone for the simple reason that, since the sun is cooler there, the hydrogen atoms are no longer fully ionized. That full ionization has allowed light to flow relatively easily from the inner core and through the outer core, but now it is coming to a stop. Now light is constantly being absorbed and re-emitted, slowing down its passage dramatically. Unless you know that star is a MS star, though, that's as far as you can go.
B stars are next to O stars, and thus fairly hot relative to other spectral types.
Since B stars show up only in two parts of the H-R Diagram, MS and WD, a B star is one or the other. Thus they can't by definition be high mass stars. On the MS, one can accurately determine a star's mass. Examine the H-R Diagram at the end of the quiz. Another key that you learned if you read the supplement on the H-R Diagram, and if you recall the placement of MS, WD, RG, and HB, is that the upper right contains the stars largest in size, while the lower left contains those smallest in size.