Calculations with logarithms

2010011005

Level: 
B
If \( a \), \( b \), \( c\in(0;\infty) \) then the expression \( \log_2a+3 \log_2 b-\frac12 \log_2⁡c \) is equivalent to:
\( \log_2\frac{ab^3}{\sqrt{c}} \)
\( \log_2\frac{3ab}{\frac12 c} \)
\( \log_2 \left({ab^3}{c}^{\frac12} \right)\)
\( \log_2 \left(-\frac32 abc\right) \)