And frankly, given my undergrad, I've had quite enough with "prestige" and its supposed make-or-break net effect. Good branding, poor reflection of reality.
Are you able to see the gap in the chain for both NA and SA? To see how the premises do or do not link up? In other words, can you prephrase the gap when going into answer choices?
You are on the right track. Strengthening and Weakening questions both focus on a gap between the premise and the conclusion. Getting familiar with those gaps should help with these question types.