Fruit Flies (Drosophila Melanogaster) Were Artificially Selected on the Basis

Fruit flies (Drosophila melanogaster) were artificially selected on the basis of having formed an association between either pineapple or orange flavors and quinine. After 15 generations, flies from selected lines were able to learn the task faster than control flies. What was it, specifically, that they were learning "faster"?

A) to identify odors of fruits suitable for egg laying, as long as the task continued to involve the original pineapple and orange flavor.
B) to identify odors of fruits suitable for egg laying, but only for the orange flavor, i.e., the ability to form an association with pineapple disappeared over generations.
C) to identify odors of fruits suitable for egg laying, but only for the pineapple flavor, i.e., the ability to form an association with orange disappeared over generations.
D) to identify odors of fruits suitable for egg laying, including novel flavors, such as apple and tomato.