Cho \(a, b, c>0\) và \(\left\{ \begin{array}{l}a \ne 1\\bc \ne 1\end{array} \right.\).

A. \(2{\log _a}\sqrt {bc}  = {\log _a}bc\)

B. \({\log _a}\sqrt {bc}  = \frac{1}{2}\left( {{{\log }_a}b + {{\log }_a}c} \right)\)

C. \({\log _a}\sqrt {bc}  = \frac{1}{{{{\log }_{\sqrt {bc} }}a}}\)

D. \({\log _a}\sqrt {bc}  = {\log _a}\sqrt b  - {\log _a}\sqrt c \)