According to paragraph 4, what did Ibn Muqla achieve around the year 900? A. He modified a set of formal scripts known as the Six Pens into rounded scripts appropriate for correspondence. B. He created a standardized set of rounded scripts proportional to the size of the first letter of the alphabet. C. He promoted calligraphy as an art form and encouraged the use of rounded letters in religious texts. D. He persuaded the court in Baghdad to use rounded styles instead of more angular scripts in their documents.