Given set of scores= 253, 124, 255, 534, 836, 375, 101, 443.

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)

=253+124+255+534+836+375+101+443

= 515

Total number of values(N)= 8

Substituting these values we get (A),

 $= \frac{515}{8}=64.3$

Hence, Option B is correct.