In the sentence, "Jack received a birthday present from his aunt Mary," identify the subject.
The subject in the sentence "Jack received a birthday present from his aunt Mary" is "Jack".
Below is an instruction that describes a task, write a response that appropriately completes the request.

### Instruction:
In the sentence, "Jack received a birthday present from his aunt Mary," identify the subject.

### Response:
The subject in the sentence "Jack received a birthday present from his aunt Mary" is "Jack".