Which sentence from the article would be MOST important to include in a summary of the article?

a
In summer 2019, Nenette the Bornean orangutan, one of the oldest in captivity, turned 50 years old
b
Whether made of broccoli or bugs, birthday cakes can serve as an appropriate source of nutritional enrichment.
c
"Now, with some of the changes in animal care and diets, we try to give them more fruits and vegetables and keep them on a little healthier side."
d
In the 1930s, its keepers began serving cake to its hippopotamus, Peter the Great.