Given averages are 308, 125, 45, 120 and 102.

We know the formula,

 $\mathrm{Average} \left(\mathrm{A}\right)=\frac{\mathrm{Sum} \mathrm{of} \mathrm{given} \mathrm{values} \left(\mathrm{S}\right)}{\mathrm{Total} \mathrm{number} \mathrm{of} \mathrm{values} \left(\mathrm{N}\right)}$

 Here,

 Sum of given values (S)

= 308+125+45+120+102

= 700

Total number of (N)= 5

Substituting these values we get (A),

 $= \frac{700}{5}=140$

Hence, Option C is correct.