The answer is B. g(x) stretches f(x) vertically by a factor of 3. Think of it this way. The log (10) = 1, log(100) = 2, ...
3 * log(10) => 3 * 1 => 3, 3 * log(100) => 3 * 2 => 6
9 * log(10) => 9 * 1 => 9, 9 * log(100) => 9 * 2 => 18
And since this value represent the Y-value on the graph, the graph is being stretched vertically by a factor f 3.
