LEDs in series without resistor
None of the above. If you wire LEDs in series, all of them will receive the same amount of current. They must, since current is number of electrons flowing through a wire per second, and the electrons must pass through all the LEDs in a series circuit.

If they all get the same amount of current, identical LEDs will all light with the same brightness. (If you have a mixture of different types of LEDs in a series circuit they will always still receive the same amount of current but that current might cause them to glow with different intensities.)