【单选题】

In every language there are two great classes of words which, taken together, consist of the whole vocabulary. First, there are those words with which we become acquainted in daily conversation, which we learn, that is to say, from the members of our own family and from our familiar associates, and which we should know and use even if we could not read or write. They concern the common things of life, and are the goods in trade of all those who speak the language. Such words may be called "popular", since they belong to the whole people; and are not the exclusive possession of a limited class.

On the other hand, our language includes a large number of words which are comparatively seldom used in ordinary conversation. Their meanings are known to every educated person, but there is little occasion to use them at home or in the market-place. Our first acquaintance with them comes not from our mother’s lips or from the talk of our school-mates, but from books that we read, lectures that we bear, or the more formal conversation of highly educated speakers who are discussing some particular topic in a style raised above the habitual level of everyday life. Such words are called "learned".And the distinction between them and "popular" words is of great importance to a right understanding of the language.
From the passage, we can infer that "popular" words are ______.A．essential to daily life
B．not regular in usage
C．convenient to use
D．not*standard enough to be used