Step 1 :The question is about hypothesis testing in statistics. The null hypothesis, which is the initial claim, states that the mean monthly cell phone bill is not higher today than it was three years ago.
Step 2 :The question states that this null hypothesis is not rejected. This means that there is not enough evidence to support the claim that the mean monthly cell phone bill is higher today.
Step 3 :Therefore, the correct answer should be B. There is not sufficient evidence to conclude that the mean monthly cell phone bill is higher than its level three years ago of $49.62.
Step 4 :Final Answer: \boxed{\text{B. There is not sufficient evidence to conclude that the mean monthly cell phone bill is higher than its level three years ago of $49.62}}.