The number of ways of selecting 10 objects out 10 identical and 20 distinct objects is

• A

  $\frac{2^{20}{-}^{20}{\mathrm{C}}_{10}}{2}$

• B

  $\frac{2^{10}{+}^{20}{\mathrm{C}}_{10}}{2}$

• C

  $\frac{2^{10}{-}^{20}{\mathrm{C}}_{10}}{2}$

• D

  $\frac{2^{20}{+}^{20}{\mathrm{C}}_{10}}{2}$