First, we determine the difference in the times between New York City and Athens. From the given above, we can conclude that the difference between the times is 7 hours. Then, we determine the time in New York when the arrived in Athens.
Time in New York : 7:30 am + (13 hours + 45 minutes)
= 21:15 or 9:15 pm of Wednesday
Then, we translate this to time in Athens by adding the difference to our answer above,
Time in Athens: 9:15 pm Wednesday + 7 hours
= 4:15 am of Thursday
Thus, the answer is letter C.