Well, no: either someone thinks the lower classes really are inferior, in which case it's covered by (b), or they don't, in which case it's (c). There's a lot of values which stem from class but people think of as objective (or at least not class based). Like having a "silly accent" or "bad taste in clothing" or "too dumb to know correct grammar" etc.

An example I thought of after posting: blackness is often associated with evil and badness, due to night being black. Dark skinned people are a group who suffer a lot of racism. As far as I can tell, this is a complete but very unfortunate coincidence (and racists have been quite happy to blur the line between them so that they're no longer so separate) But such coincidences are VERY rare, and even in this sort of case you can't ignore the consequences of the situation (ie making "dark elves" evil is skeevy even if you genuinely just mean "dark like night")