There are 10 lamps in a hall. Each one of them can be switched on independently. No. of ways in which the hall can be illuminated is

• A

  _$2^{10}-1$

• B

  _$2^9-1$

• C

  _{${\text{2}}^{\text{10}}$}

• D

  _{${\text{2}}^{\text{9}}$}