The correct option is B am I?
A question tag is a short question at the end of a statement. It changes
a declarative or imperative statement into an
interrogative one. They are mainly used to confirm something or
encourage a reply from the listener.
The question tag is like a reverse
of the sentence, it starts with the verb and ends with the subject.
Hence, the question tag that follows a positive statement will be
negative, and vice versa. The verb is generally the same as in the
sentence.
In the given sentence, "I'm" is a contraction of the subject and verb, I am. The sentence is negative, hence the question tag will be positive. The answer is: 'am I?' and option B is correct. 'Aren't I' is used as a question tag for positive statements; 'do I?' is used as a question tag when the verb in the sentence is 'don't' and 'have I?' is used as a question tag when the verb in the sentence is 'haven't'. Hence options A, C and D are incorrect.