ANSWER
A. 3 dollars / 2bars
Step-by-step explanation
We want to find the rate of change of her profit with respect to the number of candy bars.
Rate of change describes the amount of profit she makes per candy bar.
So saying that she makes a profit of $1.50 per candy bar means that every candy bar she sells yields a profit of $1.50.
If we want to rewrite this we can say:
Another way of solving this is to say that since 1 candy bar makes a profit of $1.5, then 2 candy bars will make a profit of:
2 * 1.5 = $3.
Therefore, the answer is option A.