Answer:
B.
Explanation:
The problem has got to be addition.
The sentence "Sarah is 6 years older than Amy." does not include any hint of subtracting, or multiplying.
A hint of multiplying in a expression would be the word 'times', like "Brandon is 6 times the age of Emily" which eliminates D.
A hint of subtraction in an expression would be the word 'less', like "Brandon is 6 less the age of Emily." which eliminates A and C.
The word 'older' indicates addition, or adding, and if it would have been subtraction, the keyword would be 'younger' because you are subtracting their age, like 19 - 11. The same goes with B, but adding.
Finally, we now know that it is B because there is no other addition choice.
I hope this helped. Please correct me if I am wrong.