If logax,logbx,logcx\log_a x, \log_b x, \log_c xlogax,logbx,logcx are in geometric progression, which of the following is true?
logba=logcb\log_b a = \log_c blogba=logcb
lna,lnb,lnc\ln a, \ln b, \ln clna,lnb,lnc are in harmonic progression
a,b,ca, b, ca,b,c are in geometric progression
a2=aca^2 = aca2=ac