If `log_ax=alpha,log_bx=beta,log_c x=gamma` and `log_d x=delta ,xne1` and a,b,c,`dne1`,then `log_(abcd)` x equals
A. `le(alpha+beta+gamma+delta)/16`
B. `ge (alpha+beta+gamma+delta)/16`
C. `1/(alpha^(-1)+beta^(-1)+gamma^(-1)+delta^(-1))`
D. `1/(alphabetagammadelta)`
