ANSWER IS BOTH (A) AND (C)
since through solving both logarithmic function we will get-
let, log45=x
5=4x or 5=(22)x=22x (equation one)
let, log56=y
6=5y or 6=(22x)y=22xy (from equation one)
this can also be written as: 3x2=22xy
3=22xy/21 ;which is equal to 22xy-1
so,3=22xy-1
NOW CHECK THE OPTIONS
(A) log46=xy
LHS- log226 = 1/2 log26 = 1/2 log222xy=1/2 x 2xy = xy (since 6=22xyand logaab=b x logaa = b x 1 =b [PROPERTY-1])
HENCE, LHS=RHS
CORRECT ANSWER
(B) log64=xy
LHS-log622 = 2log22xy2 = 2 x 1/2xy= 1/xy (since 6=22xy and 4=22 and logaba =1/b x logaa = 1/b x 1= 1/b [PROPERTY-2])
HENCE, LHS IS NOT EQUAL TO RHS
WRONG ANSWER
(C) log32=1/2xy-1
LHS-log32= log22xy-12 = 1/2xy-1 x log22 = 1/2xy-1 (since in starting it was proved that 3 can be written as 22xy-1 and PROPERTY-2
is also used)
HENCE , LHS=RHS
CORRECT ANSWER
(D) log23 = 1/2xy-1
LHS- log23 =log222xy-1 =2xy-1 x log22 = 2xy-1 x 1 = 2xy-1 (since 3 can be written as 22xy-1 and PROPERTY-1 is also used)
HENCE, LHS IS NOT EQUAL TO RHS
WRONG ANSWER