Based on the rhetoric Dr. King uses in his letter who is his intended audience?

His fellow clergymen were his intended audience.

Explanation:

Dr. Martin Luther King basically used repetition as a rhetoric in his Letter from Birmingham Jail. His opening words showed that the letter was directed to his fellow clergymen.

Dear fellow Clergymen,

His reference to them as "friends" and repetition of biblical examples further stress this.

Was not Jesus an extremist for love?

Was not Amos an extremist for justice?

Was not Paul an extremist for the Christian gospel?

Was not Martin Luther an extremist:

In concluding the letter, he prayed that he would meet with them not as a civil rights leader, but as a fellow clergymen and as a Christian brother.