If A is any set, then

• A

  $\mathrm{A}\cup {\mathrm{A}}^{\text{'}}=\varnothing$

• B

  $\mathrm{A}\cup {\mathrm{A}}^{\text{'}}=\mathrm{U}$

• C

  $\mathrm{A}\cap {\mathrm{A}}^{\text{'}}=\mathrm{U}$

• D

  None of these