According to Edwin Shneidman, _____, or a feeling of intolerable psychological pain, is an underlying key to suicide.

What do all mood disorders have in common?

A. The presence of a negative mood state B. They are at least six months in duration. C. The presence of irrational thoughts D. They are characterized by emotional extremes.

Down syndrome is caused by

a. a missing chromosome. b. two X chromosomes. c. an extra 21^st chromosome. d. the presence of an X and a Y chromosome.