A、4,000. B、 3,000. C、 9,000. D、 7,000. AHow many inhabitants on that island were NOT involved in glassmaking industry?

In the Middle Ages, the Italian city of Venice assumed its role as the glassmaking centre of the western world. The Venetian merchant fleet ruled the Mediterranean waves and helped supply Venice’s glass craftsmen with the technical know-how of their counterparts in Syria, and with the artistic influence of Islam. The importance of the glass industry in Venice can be seen in the number of craftsmen at work there(more than 8,000 at one point).
    Until the end of the 13th century, most glassmaking in Venice took place in the city itself. However, the frequent fires caused by the furnaces led the city authorities, in 1291, to order the transfer of glassmaking to the island of Murano. The measure also made it easier for the city to keep an eye on what was one of its main assets, ensuring that no glassmaking skills or secrets were exported.
    In the second half of the 15th century, the craftsmen of Mnrano started using quartz sand and potash made from sea plants to produce particularly pure crystal. By the end of the 16th century, 3,000 of the island’s 7,000 inhabitants were involved in some way in the glassmaking industry.