Since the late 1930s the Bureau of Indian Affairs of the United States has been working to

Since the late 1930s the Bureau of Indian Affairs of the United States has been working to promote native language literacy among Indians. Indians were to be taught to read and write in their native language before being taught English. Studies in many cultures around the world demonstrate that children learn to read best in their mother tongue. Bilingual reading books and other educational materials were prepared in Navaho, Hopi, Siouan, Pueblo, and Papago languages. The difficulties were tremendous because many American Indian languages are distinctively different in structure from all other languages in the world. They do not have "words" in the sense that other languages do—as independent meaningful sound sequences that combine into "sentences". Their "sentences" are made by combining prefixes, infixes, and suffixes into what looks like one long word but is essentially the equivalent of our sentence. It is impossible, in other words, to make an Indian utterance that is not a sentence. In our sense, Indian languages do not have parts of speech, conjugations etc. The sentence is the smallest structure available to speakers of the language. Therefore bridging the translation gap between English and such language is a massive feat. In most cases, Indian children need to be bilingual though not necessarily be literate. That is, they need to speak their native language to participate fully in their home and tribal affairs. But, they do not need to read and write that language. On the other hand, they also need a reading, writing, and speaking knowledge of English, not only to get their due in this country but, ironically, also to preserve their heritage.

In the first sentence "literacy" means______.

A．freedom

B．concerning literature

C．quality

D．being able to read and/or write

请帮忙给出正确答案和分析，谢谢！