Given set of scores= 556, 224, 778, 442, 336, 112

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)

=556+224+778+442+336+112

= 2448

Total number of values (N)= 6

Substituting these values we get (A),

 $= \frac{2448}{6}=408$

Hence, Option D is correct.