how to structure json response code example

Example 1: api response format

POST http://localhost:60464/api/student?age=15 HTTP/1.1
User-Agent: Fiddler
Host: localhost:60464
Content-Type: application/json
Content-Length: 13

{
  id:1,
  name:'Steve'
}

Example 2: api response format

public class Student
{
    public int Id { get; set; }
    public string Name { get; set; }
}

public class StudentController : ApiController
{
    public Student Post(Student student)
    {
        // save student into db
        var insertedStudent = SaveStudent(student);

        return insertedStudent;
    }
}