Paper industry needed a new source of fiber in the

单项选择题

Questions 14 to 17 are based on the following passage. At the end of the passage, you will be given 20 seconds to answer the questions.
Now listen to the passage.

Paper industry needed a new source of fiber in the early 1800s is because ______.

A．people wanted higher quality paper
B．paper made from rags deteriorated too quickly
C．wood pulp had become too expensive
D．the supply of rags was insufficient