Answer:
 Reflect the graph of f across the y-axis and then reflect across the x-axis.
Explanation:
Reflection rules:
Reflection over x -axis:(x,y)→(x,-y)
Reflection over y-axis : (x,y)→(-x,y)
Graph:

We are given that the graph of f into the graph of g.
 
 and
 and 

Reflect over y axis.
Reflected graph 

Reflect the obtained graph over x axis

So, Option B is true 
Hence Reflect the graph of f across the y-axis and then reflect across the x-axis.