Folklorist: Oral traditions are often preferable to written ones.
Conclusion
Oral traditions are preferable to written one.
Evidence
Oral traditions (which require exclusive dependence on speech) improve the memory, whereas literate populations (which presumably have written histories) end up with sluggish recall because they can just run to written sources as needed.
Also, writing has no limits (presumably memory / oral traditions do have limits), so it can become so abundant that both writer and reader become confused.
Meanwhile, oral traditions don't suffer from the same accumulation of excess material, because whatever's useless / irrelevant is quickly eradicated.
Evaluate
We ascertain that the first sentence is the Main Conclusion because of the opinion indicator "preferable", combined with the fact that the author proceeds to support that opinion with the rest of the paragraph.
There are two main advantages offered in the evidence for why oral history is better than written history:
1. Oral is better for the memory 2. Oral is less likely to lead to an overabundance of material (which can confuse the audience and the speaker)
Goal
Since there are two premises, either one might be involved in how the correct answer strengthens. We can pre-phrase what each of those sounds like
1. Whichever tradition is better at improving / maintaining memory is preferable.
or
2. Whichever tradition is better at pruning away useless, excessive material so that the speaker/reader are clearer on what remains is preferable.