The value of an independent variable is determined by a subject's behavior.

Which of the following statements is true regarding the understanding of the meaning of numbers?

a. Research has found that some nonhuman animals have a primitive awareness of numeracy. b. Children begin to count at the age of 5. c. Children who have problems learning to read often excel at mastering math skills. d. Dyslexia refers to a difficulty in processing numbers.

In which kind of study would a researcher determine how many and which relatives of a person with a disorder have the same disorder?

a.) twin study b.) adoption study c.) family pedigree study d.) generational extraction study