Studies show that only about 1 out of every 10 U.S. citizens say they are "very happy."

Approximately how many different human languages are being spoken today?

a. 3,000. b. 5,000. c. 2,000. d. 750.

With the exception of the sex cells, every cell in the human body contains

a. 23 chromosomes. b. 46 chromosomes. c. 23 recessive genes and 23 dominant genes. d. 46 heterozygous pairs.