By following that rule, choose the option from the given sets that follows the rule applied in the given set (6, 18, 54).

Explanation

As, $6 \xrightarrow{\times 3} 18 \xrightarrow{\times 3} 54$ Similarly, (from option a) $15 \xrightarrow{\times 3} 45 \xrightarrow{\times 3} 135$ Therefore, option (a) is the correct answer.