Select the sentence that does not contain a grammatical error.
A. His behavior had been irresponsible and unbelievabley childish.
B. His behavior had been irresponsable and unbelievably childish.
C. His behavior have been irresponsible and unbelievably childish.
A. His behavior had been irresponsible and unbelievably childish.
Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
Select the sentence that does not contain a grammatical error.

### Response:
A. His behavior had been irresponsible and unbelievably childish.