an article question

[Grinkl]

Dear teachers.

I wonder which is correct in this question.

Q: He is ( ).

1. Duke of Alencon, younger brother of the French King Henry
2. the Duke of Alencon, younger brother of the French King Henry
3. Duke of Alencon, the younger brother of the French king Henry
4. the Duke of Alencon, the younger brother of the French king Henry

Regards!

[Buddhaheart]

An article may be omitted in front of a proper noun. However, it’s usually required in front of a common noun. Hence I think #3. (He is Duke of Alencon, the younger brother of the French King Henry) is appropriate.

[Grinkl]

An article may be omitted in front of a proper noun. However, it’s usually required in front of a common noun. Hence I think #3. (He is Duke of Alencon, the younger brother of the French King Henry) is appropriate.

Thank you so much. How about my small opinion that Duke of Alencon is the complement in the sentence, so the is omitted, i think? But I think the Duke of ~ pattern appears many times.that's why i am confused. Is also 4 a possible answer?