Passage Two
How men first learned to invent words is unknown. All we really know is that men, unlike animals, somehow invented certain sounds to express thoughts and feelings, actions and things, so that they could communicate with each other; and that later they agreed upon certain signs, called letters, which could be combined to represent those sounds, and which could be written down. Those sounds, whether spoken or written in letters, we call words.
The power of words, then, lies in their associations--the things they bring up before our minds. Words become filled with meaning for us by experience; and the longer we live, the more certain words recall to us the happy and sad events of our past; the more we read and learn, the larger the number of words that mean something to us becomes.
Great writers are those who not only have great thoughts but also express these thoughts in words which appeal powerfully to our minds and feelings. This attractive use of words is what we call literary style. Above all, the real poet is a master of words. He can express his meaning in words which sing like music, and, by their position and association, can move men to tears. We should therefore learn to choose our words carefully and use them correctly, or they will make our speech dull and silly.
Which of the following did men invent first？

A. Words.
B. Sounds.
C. Signs.
D. Letters.