How many categories does researcher John Holland use to describe personality categories that one should consider when matching a person with a prospective occupation?

What is the number one use of the Internet as measured by the number of hits, the number of websites, or the amount of money spent?

a. dating b. social networking c. pornography d. information gathering/learning

__________ are responsible for myelination

A) Neurons B) Neurotransmitters C) Glial cells D) Synapses