Consider the numbers a=m^{\frac{8}{3}},b= m, c=m^{-\frac{2}{3}}
They are in GP, and we have\log_ca, \log_b c, \log_ba are the numbers -4, -\frac{2}{3}, \frac{8}{3} which are in AP with common difference -\frac{10}{3}.
So none of the options are right!