Electric bug zappers, which work by attracting insects to light, are a very effective means of ridding an area of flying insects. Despite this, most pest control experts now advise against their use, recommending instead such remedies as insect-eating birds or insecticide sprays. Which one of the following, if true, most helps to account for the pest control experts' recommendation? ['Bug zappers use more electricity but provide less light than do most standard outdoor light sources.', 'Insect-eating birds will take up residence in any insect-rich area if they are provided with nesting boxes, food, and water.', 'Bug zappers kill many more beneficial insects and fewer harmful insects than do insect-eating birds and insecticide sprays.', 'Developers of certain new insecticide sprays claim that their products contain no chemicals that are harmful to humans, birds, or pets.']