The word "dean" in the beginning sentence of the first paragraph means______.

A．Lithic technology was useful to the understanding of cultural history.
B．Crabtree was always willing to share his knowledge with others.
C．Crabtree's Law argues that the final finishing state in producing stone artifacts should be barred in fiintknapping.
D．Stone tool analysis mainly consists of investigating the technological processes by which the tools were produce

A．malignant cells in him were unable to develop into deadly ones
B．he was a generous man with immense energy and curiosity
C．the Lithic Lab at the Ohio State Museum employed him
D．he was determined that he was able to deter the disease