A farmer was planting a huge field of sunflowers for the purpose of earning a living from sunflower seeds. The farmer then decided to cross his original sunflowers with an improved breed of sunflower resistant to insects. Which statement best describes what the farmer was doing?
A
He was developing an garden of pretty flowers.
B
He was using asexual reproduction to produce cloned flowers.
C
He was pollinating with bees.
D
He was using selective breeding to improve the traits of his sunflower crop.
D
He was using selective breeding to improve the traits of his sunflower crop.