Which of the following statements best explains why "the second of these was the more seri

Which of the following statements best explains why "the second of these was the more serious impediment" (Lines 5-6 Para. 3)？

A．Chemical knowledge was limited to a small number of people.

B．The symbolic language used was very imprecise.

C．Very few new discoveries were made by alchemists.

D．The records of the chemical processes were not based on experiments.