What percentage of Americans over age 65 years have lost all of their natural teeth?

Reduced levels of which neurotransmitter lead to Parkinson's disease?

a) GABA b) dopamine c) serotonin d) acetylcholine

Tens of millions of young people in the United States take part in community-based

A) arts and crafts clubs. B) political organizations. C) sports. D) weight loss programs.