Describe the Transformations Required to Obtain the Graph of the Function

Multiple Choice

Describe the transformations required to obtain the graph of the function f(x) from the graph of the function g(x) .
- $$f ( x ) = - 6 \cos 3 x ; g ( x ) = \cos x$$

A) Horizontal shrink by a factor $\frac { 1 } { 6 }$ , vertical stretch by a factor of 3 , reflection across $y$ -axis
B) Horizontal stretch by a factor 3 , vertical stretch by a factor of 6 , reflection across $x$ -axis
C) Horizontal shrink by a factor $\frac { 1 } { 3 }$ , vertical stretch by a factor of 6 , reflection across $\mathrm { y }$ -axis
D) Horizontal shrink by a factor $\frac { 1 } { 3 }$ , vertical stretch by a factor of 6 , reflection across $x$ -axis