Refer to figure.
ICAO FLIGHT PLAN

INSERT the first cruising speed as in (a) and the first cruising level as in (b), without a space between them. 
THEN, following the arrow, INSERT the route description as in (c).

INSERT the True airspeed for the first or the whole cruising portion of the flight, in terms of: 
Kilometres per hour, expressed as K followed by 4 figures (e.g. K0830), or 
Knots, expressed as N followed by 4 figures (e.g. N0485), or 
True Mach number, when so prescribed by the appropriate ATS authority, to the nearest hundredth of unit Mach, expressed as M followed by 3 figures (e.g. M082).

INSERT the planned cruising level for the first or the whole portion of the route to be flown, in terms of: Flight level, expressed as F followed by 3 figures (e.g. F085; F330), or 
When so prescribed by the appropriate ATS authorities: Standard metric level in tens of metres, expressed as S followed by 4 figures (e.g. S1130), or 
Altitude in hundreds of feet, expressed as A followed by 3 figures (e.g. A045; A100), or 
Altitude in tens of metres, expressed as M followed by 4 figures (e.g. M0840), or 
for uncontrolled VFR flights, the letters VFR.

For this question we are given cruising speed in IAS. Therefore, we must convert it to TAS using the flight computer.

FIRST STEP: using the “AIR SPEED” window, set the altitude 8000 ft and align it to its ISA temperature (15 – 2 x 8 = -1ºC). 
SECOND STEP: Look for the 90 in the inner scale of CAS. Note that it aligns with 102 kt (outer scale) 

Closest option is, therefore, N0100.