Answer :

To evaluate [tex]\( \log_4 256 \)[/tex], we need to determine the power to which the base 4 must be raised to obtain 256.

The expression [tex]\( \log_b(a) = c \)[/tex] means that [tex]\( b^c = a \)[/tex]. Therefore:
[tex]\[ \log_4(256) = x \][/tex]
implies
[tex]\[ 4^x = 256 \][/tex]

Next, we should recognize if 256 can be expressed as a power of 4. We proceed by determining the power relationship here:

[tex]\[ 4^1 = 4 \\ 4^2 = 16 \\ 4^3 = 64 \\ 4^4 = 256 \][/tex]

We see that:
[tex]\[ 256 = 4^4 \][/tex]

Therefore:
[tex]\[ 4^4 = 256 \][/tex]

This means:
[tex]\[ \log_4(256) = 4 \][/tex]

Thus, the correct answer is:

A. 4