What is the passage mainly about?

Câu hỏi: Read the following passage and mark the letter A, B, C, or D to indicate the answer to each of the question.
Ostriches are the largest and heaviest birds on earth. They can grow to be as tall as 9 feet and can weigh as much as 250 pounds. Even though they have wings, they cannot fly. Instead, ostriches have long, powerful legs that help them to run very fast when they feel threatened. Ostriches use their wings to move themselves forward and to help them change direction.
Ostriches are native to Africa, where they still live in desert areas and dry, open grasslands called savannahs. Ostriches can also be found in zoos all over the world. Humans have domesticated ostriches, so now ostriches live on farms in over a dozen countries, including the United States, China, India, Japan, Brazil and Costa Rica. They are raised for their meat, skin, and feathers.
Ostriches like to live in small groups called herds. The male ostrich is called a rooster; the female, a hen. Baby ostriches are called chicks. The female ostrich lays the eggs, but both the male and the female take turns sitting on the eggs to keep them warm.
(Adapted from Readtheory.org website)
What is the passage mainly about?
A. the male and female ostriches
B. all about eggs of ostriches
C. distribution and habitat of ostriches
D. facts about ostriches and their habits