Question regarding pay for hours of labor

I have a brief question regarding pay for employees working a shift from 3AM - 11:30AM. I understand that there is a required 15% differential paid for employees working the early morning hours.

Here is the real question. Do each of the hours need to be paid at 15% for this shift, or only the hours between 3AM-7AM.

Which is correct:

A: 8 hours worked between 3AM - 11:30AM. All hours paid at regular pay, plus 15% differential.

B: 8 hours worked between 3AM - 11:30AM. 8 hours paid at regular pay, plus 4 hours paid at 15%.

[Fabio J. Guzman]

Daytime work hours range from 7:00 a.m. to 9:00 p.m. (Art. 149 of the Labor Code). A work shift is considered a daytime shift as long as no more than three hours exceed the 9:00 p.m. limit. Otherwise it is considered a night shift (Art. 140 of the Labor Code). A 3 a.m to 11:30 a.m. shift has more then three night hours. Therefore, it is considered a night shift and should paid with a 15% increase for the whole shift.