Solution -

Let us analyse the answer choices -

A. Often manufacturers introduce a new grocery product in order to take business away from a competitor who already produces a similar product. - This is irrelevant because it is talking about why manufacturers introduce new products. It helps our case that the grocer will get nothing extra out of it.

B. Some manufacturers prefer to put new grocery products in stores as early as possible, rather than spending time and money on controlled market research. - This is also irrelevant as it is talking about what manufacturers want.

C. Most grocery stores have such narrow profit margins that they cannot afford to carry marginally successful products. - We don't know what the profit margins are for old and new products. So, this option is incorrect as well.

D. Grocers have the option not to take on products that they do not think will sell well, or that they expect will not increase the grocer's profits. - What we are discussing is whether the grocers have a reason to take on new products and whether they would like to take on new products or not. This just tells us that they can pick their own products as per their choice. What we want to know is whether new products will be a preferred option for the grocers or not.

E. Some manufacturers introduce new types of groceries, such as pre-cooked meals that people can prepare quickly instead of going to a restaurant. - Our conclusion depends on the fact that one brand just replaces another brand and hence there is no value added for the grocer. This option tells us that there are some new products which are basically "new types of products" and not just new brands. This could increase the overall sales and provide a reason for the grocer to introduce new products.
So, the correct answer is Choice E.