Final answer:
Martha Karolyi gave Gabby Douglas the nickname 'Golden Girl' due to her outstanding performances in gymnastics, especially during the 2012 London Olympics where she won multiple gold medals. Therefore, the correct answer is b) Golden Girl.
Step-by-step explanation:
The nickname Martha Karolyi, the national team coordinator, gave Gabby Douglas was Golden Girl. Martha Karolyi was known for her ability to spot talent and played a significant role in the success of the U.S. gymnastics team during her tenure.
Gabby Douglas earned this nickname because of her stellar performances, particularly at the 2012 London Olympics where she won gold medals in both the individual all-around and team competitions.
Her excellence in gymnastics and her achievements, including becoming the first woman of color of any nationality and the first African-American gymnast in Olympic history to become the Individual All-Around Champion, contributed to her being bestowed with the Golden Girl nickname by Karolyi.