First the question stem asks us to accepts their sales figures are accurate.

Besides of the sentences pointed out in Kevin's explanation, this portion of the sentence from the Accountant, which is the description of the sales figures, should also be taken into account:

given that this group of restaurants—the only ones for which we have sales figures that permit a comparison between last year and the year before

This allows the possibility that some restaurants' sales not being in records. If the sales manager's statement is also true, the company knows how much were sold in total, but certain individual restaurant's sales can be unknown. For example:

2 years ago total: 100

last year total: 150

let's say there are 10 restaurants with 5 of known sales and 5 of unknown sales

the average of the the group of restaurant that they have sales figures to compare 2 years ago: 10

5 x 10 + 5 x 10 = 100

• the second 5 corresponds to the restaurants with unknown sales, 10 being their average

the average of the the group of restaurant that they have sales figures to compare last year: 5

5 x 5 + 5 x 25 = 150

With that sentence from the accountant we don't need to assume the number of restaurants increased.

#help

#help

To me E still has these problems:

1. Persuading them to relocate doesn't mean you'll be able to hire them, let alone they don't even have to be in the education industry after they move.

2. Training more teachers is also another way of increasing the number of qualified teachers in that region. If there is another way to achieve the increase in the amount of qualified teachers, then E will not be a necessary assumption.