Which of the following components of behavioral skill training (BST) was determined to have the most impact on with way intervention was delivered?

According to the research on infant speech perception,

a. infants cannot distinguish between their native language and an unfamiliar language until they are about 1 year of age. b. infants' ability to appreciate phoneme contrasts in an unfamiliar language improves substantially during the first two years of life. c. infants are slow to develop language because they cannot recognize the basic phonemes of their native language until they are about 9 months of age. d. by the age of about 5 months, infants respond more to their own name than to a different name.

Kathy takes her 2-year-old son to the supermarket every Saturday. Each week, the same sequence of events unfolds: Her son screams, demanding that Kathy buys him treats. Although she refuses to give in to his demands, he continues to scream

Finally, Kathy yells at the top of her lungs, "QUIET!" He stops screaming instantly. What operant conditioning concepts are illustrated in this story? A) Kathy is using negative reinforcement to increase her son's screaming. B) Kathy is using punishment to suppress the screaming; her use of punishment is negatively reinforced by the cessation of screaming. C) Kathy's son probably learned how to scream by observing his parents at home, and now he is reinforced on a variable-interval schedule of reinforcement. D) Kathy's son probably learned how to scream by observing his parents at home, and now he is reinforced on a fixed-ratio schedule of reinforcement.