If an individual practices propriety of social stratification it basically means that they hang out with those whom they consider to be their social equals or superiors, while also observing levels of peoples they consider to be beneath them, or even beyond the the reach of their social status.

propriety is ‘proper’

stratification is ‘levels’

What does “propriety” mean? If you’re clueless, or kind of know but aren’t sure, look it up.

Got that? Good. Now, what’s “social stratification”? I assume that this is within the context of a class or book, so you’ll want to look to it for the type of social stratification the question’s talking about.

There, not so hard at all, was it?