Answer: Choice C
Reason:
The bases for the 1st and 2nd expression are 2 and 4 respectively. The bases do not match, which is why the expressions aren't equivalent for choice C.
The general template is
where both bases are "b". This transformation is useful to help isolate the exponent.
Choice A is a valid example of where we go from log form to exponential form, or vice versa. Take note the bases are the same here (both 2).
Choice B is also valid since the bases are 3 each.
Choice D is valid as well. Writing "log" without a stated base has us assume the default of base 10. The fraction 1/10 is equivalent to the decimal form 0.1