The conclusion is that two years ago the newspaper company reorganized its sales strategies and that led to increase in advertising sales.
A--In the past two years advertising sales have increased, therefore, net revenue from sales must have increased also. What would be helpful is to measure the proportion of net sales revenue prior to the reorganization that took place two years ago with revenue generated in the past two years.
B--increase in net advertising sales. This is direct measurement of how well your sales strategy is doing. If you read the question, the effort of the newspaper company was to increase its sales by reoragnizing its sales force and restructuring its sales strategies. What could be a better indicator then this?
C--OK, here's the trap that GMAC has set for us. However, if you read the choice, it is a logical alternative explanation that perhaps old non-productive sales people left and now they've been replaced with new productive people. Trust me I almost went for this one. Remember this is a weaken the arguement and strengthen the arguement question in disguise. Whenever you come across a question like this, look for logical alternative explanations. If there is one, then it usually strengthens the questions, such as this case.
D--Again, this is a direct measurement of what worked and what didn't work before the reorganization effort. Highly relevant to understanding increase in sales.
E--Growing economy means people have more money and they want to buy more products, therefore, businesses will advertise more. This can be an alternative explanation to why sales increased. Therefore, it's relevant to the arguement.
I hope this helps.
Andrew