Answer:
B.
Step-by-step explanation:
Let's find g(f(x)) for each choice for fun and so you can have more examples:
A) f(x)=3x and g(x)=sqrt(x)+1
so g(f(x))=g(3x)=sqrt(3x)+1
So definitely not this choice
B) f(x)=x+1 and g(x)=sqrt(3x)
so g(f(x))=g(x+1)=sqrt(3(x+1))
So this one works! :)
C) f(x)=sqrt(x)+1 and g(x)=3x
so g(f(x))=g(sqrt(x)+1)=3(sqrt(x)+1)
Not this one!
D) f(x)=sqrt(3x) and g(x)=1
g(f(x))=g(sqrt(3x))=1
