The correct representation of the repeating decimal for \( \frac{6}{11} \) using bar notation is \( 0.\overline{54} \). Among the options provided, none of them explicitly use bar notation, but \( 0.54 \) implies that \( 54 \) repeats.
So, if we align this understanding with the choices given, the most appropriate option representing the repeating decimal is:
0.54 (implying that 54 repeats)
However, if bar notation were to be used explicitly, it would be represented as \( 0.\overline{54} \).