Isn't the mechanism of aqueous sodium hydroxide and 1-bromobutane involves both heterolytic bond fission and attacking by a nucleophile? What is involved in the mechanism of the reaction between aqueous sodium hydroxide and 1-bromobutane?

A. attack by a nucleophile on a carbon atom with a partial positive charge

B. heterolytic bond fission and attack by a nucleophile on a carbocation

C. homolytic bond fission and attack by an electrophile on a carbanion

D. homolytic bond fission and attack by a nucleophile on a carbocation

I think that A and B would be correct answers, but the correct answer is only A. Bromine accepts both two electrons from the carbon atom and the nucleophile attacks on that carbocation of the carbon atom. Why choice (B) is incorrect? I also searched the internet and found that this reaction is SN1, but why it occurs with the primary carbon, which is usually a reactant in SN2 reaction.
Well your thinking is absolutely right but only for tertiary halogenoalkane as this is a prinary halogenoalkane it will follow SN2 mechamism. In which necleophile attacks on a partial positive carbon