Millions of homes are now using low-energy lighting, but millions more

Millions of homes are now using low-energy lighting, but millions more have still to make the switch, a fact that the government and the home lighting industry are eager to change. Although low-wattage bulbs cost more per bulb than normal bulbs, their advantages to the homeowner are enormous, and therefore everyone should use low-wattage bulbs.

Information about which one of the following would be LEAST useful in evaluating the argument?

(A) the actual cost of burning low-wattage bulbs compared to that of burning normal bulbs
(B) the profits the home lighting industry expects to make from sales of low-wattage bulbs
(C) the specific cost of a low-wattage bulb compared with that of a normal bulb
(D) the opinion of current users of low-wattage bulbs as to their effectiveness
(E) the average life of a low-wattage bulb compared with that of a normal bulb