We can't really answer this question based on the information provided in the 2 options, so the answer should be E.
Initially, we are told that premium and regular quality shirts are purchased at 'various prices'. For simplicity sake lets assume all premium cost a and all regular cost b. and lets assume that the number of these shirts is x and y respectively. Next, we know that the average price of these shirts combined is 40$. => Cost Price of shirts for Fairview Department Store = 40(x+y)
About the selling price, we know that a,b both now have a markup of 50% so the selling price (aka original retail price) is 3a/2 and 3b/2.
This is all the things we know from the question, now we'll look at the options.
(1) 80% of the shirts were sold at the original retail price.
Here it would seem that technically the SP for 80% of the shirts should be 80% of 40(3/2)(x+y) from our previous understanding of Cost Price, but we dont know what share of premium vs regular shirts have been sold, neither do we know what is the price difference of the 2 types of shirts. We can't tell how much money could have been made as profit here. Nor can we tell how much of the Cost Price we would still have to offset from the remain 20% shirts to tell if we made a profit.
=> INSUFFICIENT
(2) Markdown price is 12$ per shirt.
Here, we still don't know how much profit we would have made while selling at the original retail price, and neither do we know how much of a loss are we incurring by selling shirts at 12$ across the board.
=>INSUFFICIENT
(1) + (2)
Even considering the 2 together, we would still not know the profit made over the first 80% of the shirts or the loss incurred on the remain of the 20% of the shirts coz we don't know the original retail price
=> INSUFFICIENT
Therefore, E is correct