下列哪种灯具的下半球光通量比值(所占总光通量的百分比)为直接型灯具

A．90%～100%
B．60%～90%
C．40%～60%
D．10%～40%

It is commonly held among marketing experts that in a nonexpanding market a company’s best strategy is to go after a bigger share of the market and that the best way to do this is to run comparative advertisements that emphasize weaknesses in the products of rivals. In the stagnant market for food oil, soybean-oil and palm-oil producers did wage a two-year battle with comparative advertisements about the deleterious effect on health of each other’s products. These campaigns, however, had little effect on respective market shares; rather, they stopped many people from buying any edible oils at all.
The statements above most ply support the conclusion that comparative advertisements

A．increase a company’s market share in all cases in which that company’s products are clearly superior to the products of rivals.

B．should not be used in a market that is expanding or likely to expand.

C．should under no circumstances be used as a retaliatory measure.

D．carry the risk of causing a contraction of the market at which they are aimed.

E．(E) yield no long-term gains unless consumers can easily verify the claims made.