Which form of the modifier best completes the sentence?

of the twins, jeff is the listener.

a.
best

b.
bestest

c.
better

d.
more better

Right of the bat, we know that options B and D are incorrect because the go against the grammatical rules for comparatives and superlatives. That leaves us with the real question, what should we use here? Comparatives or superlatives?

Because the example sentence mentions twins (a pair of siblings) we can conclude that a comparative would be the best modifier to use. Take into consideration that comparatives come along with a specific grammatical structure (subject + to be + comparative + than + object [Jeff is a better listener than Twin B]). In this case, Jeff is the better listener.