Step 1: Express 81 as a power of 3
We know that:
\[
81 = 3^4
\]
Step 2: Use the logarithmic identity
We use the logarithmic identity \( \log_b a^n = n \log_b a \), so:
\[
\log_3 81 = \log_3 (3^4)
\]
Step 3: Apply the logarithmic rule
By applying the rule \( \log_b (b^n) = n \), we get:
\[
\log_3 (3^4) = 4
\]
Answer: Therefore, \( \log_3 81 = 4 \). So, the correct answer is option (2).