Respuesta :
Answer:
B) The addition of dried apples and raisins to the formula.
Explanation:
Based on the excerpt above, Dr. Elsa Birde noticed the increase in the number of songbirds in his bird feeders after she added the new mixture into the feeds. Addition of mixture of dried apples and raisins in the usual feed of sunflower seeds, millet, thistle seed and cracked corn was a new plan of hers to try out on the birds. And she found that it was successful in bringing about the increase in the birds. Also, this increase is not just a one time thing. She kept recording the result for more than three years and the results remained the same. That is why she is also planning put the formula into production for others to experience the same increase. Thus, it can be safely said that the increase in the songbirds at the bird feeders is due to the addition of the new mixture to the formula.