How much heat do you need to raise the temperature of 150 g of oxygen from -30c to -15c?

The amount of heat needed to raise the temperature of a substance by  is given by

where
m is the mass of the substance
Cs is its specific heat capacity
is the increase in temperature

For oxygen, the specific heat capacity is approximately 

The variation of temperature for the sample in our problem is 

while the mass is m=150 g, so the amount of heat needed is

The answer is a.  i hope this