Read the paragraph. Braille is a system of communication used by the blind. It was developed by Louis Braille, a blind French student, in 1824. The code consists of an alphabet using combinations of small raised dots. The dots are imprinted on paper and can be felt, and thus read, by running the fingers across the page. The basic unit of the code is called a "cell" that is two dots wide and three dots high. Each letter is formed by different combinations of these dots. Numbers, punctuation marks, and even a system for writing music are also expressed by using different arrangements. These small dots, which may seem insignificant to the sighted, have opened up the entire world of books and reading for the blind. Which answer contains two details presented in the paragraph?

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