Which Statement Best Describes What Today's IQ Scores Represent

Which statement best describes what today's IQ scores represent?

A) Performance of adults 16 to 89 years of age on a number of individual verbal and nonverbal tasks
B) The ratio of a child's mental age divided by his or her chronological age, then multiplied by 100
C) A person's performance on intelligence tests relative to a comparison group of people
D) The degree to which a measurement tool produces consistent, repeatable results