This is a simple "True Altitude" question.
The Safety Altitude is measured from Sea Level.
The QNH provided is of course the sea level pressure.
However, the temperature of the column of air between sea level and the aircraft does not conform to the International Standard Atmosphere (ISA) as it is ISA +10. Thus the altimeter which is calibrated using the ISA will not show the true altitude.
Remember for temperature - "high to low look out below" because the altimeter will over read.
In this case, the temperature is higher than standard so the altimeter will under read. So the answer is either a or b.
Use your Whizz wheel to tell you what the indicated altitude would be when the true altitude is 12000ft and the temperature is +1C (ISA+10).
Regards,
DFC