Answer: Option B
$$\eqalign{
& {\text{A = Since lo}}{{\text{g}}_a}a = 1,{\text{ so lo}}{{\text{g}}_{10}}10 = 1 \cr
& \cr
& B = \,{\text{log}}\left( {2 + 3} \right) = 5\, \cr
& \,\,\,{\text{and log}}\left( {2 \times 3} \right) = {\text{log}}6 \cr
& = {\text{log}}2 + {\text{log}}3 \cr
& \therefore \,{\text{log}}\left( {2 + 3} \right) \ne {\text{log}}\left( {2 \times 3} \right). \cr
& \cr
& C = \,{\text{ Since lo}}{{\text{g}}_a}1 = 0,so{\text{ lo}}{{\text{g}}_{10}}1 = 0. \cr
& \cr
& {\text{D = log}}\left( {1 + 2 + 3} \right) = {\text{ log}}6 \cr
& = {\text{ log}}\left( {1 \times 2 \times 3} \right) \cr
& = {\text{ log}}1 + {\text{ log}}2 + {\text{ log}}3. \cr
& {\text{So (B) is incorrect}} \cr} $$