Pain perception is not influenced by emotional reactions

The earliest prenatal testing is a first-trimester screening that combines two popular forms of prenatal testing. This test combines which two popular prenatal tests?

a. sonogram and amniocentesis c. blood test and sonogram b. embryoscopy and fetal blood sampling d. chorionic villus sampling and blood test

Nicholas and Tyler are two young men who are childhood friends. Nicholas teaches Tyler to ride a bicycle, and Tyler teaches Nicholas swimming. According to the social-exchange theory, which of the following is exhibited by Nicholas and Tyler in this scenario?

A. the social-responsibility norm B. the bystander effect C. the reciprocity norm D. the overjustification effect