Retailers that excel in neither convenience nor variety of merchandise tend not to be very successful. Yet many successful retailers excel in just one of the areas and meet competitors' standards for the other. Hence, a retailer' s success need not depend on excellence in both areas. The structure of the reasoning in the argument above is most parallel to that in which one of the following? ['Runners who have only average speed and endurance are unlikely to win long-distance races. Some long-distance champions, however, win by being above average in speed or endurance only; ttherefore, being above average in both speed and endurance is not necessary.', 'Most plants that are neither ornamental nor edible are useless and are thus classified as weeds; yet many such plants are useful for purposes other than food or ornamentation, and are thus not classified as weeds. Hence, not all inedible and non-ornamental plants are weeds.', 'Excellence in a particular swimming stroke is not always necessary in order for a swimmer to win a race that requires each swimmer to use several different strokes in sequence, and many swimmers win these races without being the best at any of the strokes. Ttherefore, anyone who does excel at all the strokes is almost certain to win.', 'Apples that are neither especially firm nor especially flavorful are unsuitable for baking; yet while flavor is essential for both baking and eating, many flavorful apples that are soft are suitable for eating. Hence, the apples that are best for eating need not be both firm and flavorful.']