Down syndrome is caused by
A. an extra 21st chromosome
B. a missing 21st chromosome
C. lack of oxygen at birth
D. unknown influences
A. an extra 21st chromosome
You might also like to view...
Which of the following factors influences the effectiveness of punishment?
a. immediacy b. contingency c. motivating operations d. all of these
In a two-factor study, it is possible to have one experimental factor and one nonexperimental factor
a. True b. False Indicate whether the statement is true or false
In which section of a psychological research report should the hypothesis of the study be stated?
a. results b. method c. introduction d. references
When children understand that rolling a ball of clay into a "snake" does not increase the amount of clay or that pouring liquid from a tall, narrow glass into a shallow dish does not reduce the amount of liquid, the children have mastered
a. animism. b. object permanence. c. conservation. d. egocentrism.