Tyra is babysitting her sister's infant daughter when the mail arrives. There is a package to be signed for, and Tyra asks the carrier to step inside because of the weather. He smiles at Tyra's niece, who hides her face in Tyra's shoulder and then looks back at him with concern. What has happened here?a. Happiness was expressed by the social smile, evoked by a human face.
b. Stranger wariness occurred when an infant expressed concern when an unknown person appeared.
c. Separation anxiety was expressed in tears, dismay, or anger when a familiar caregiver left.
d. Infants progress from reactive pain and pleasure to complex patterns of social awareness.

B. Stranger Wariness occurred when an infant expressed concern when an unknown person appeared

Explanation:

In the question, Tyra's niece simply hides her face and looks back at the carrier with concern. She isn't smiling, crying, throwing a tantrum, or showing symptoms of answer D, but in B she is doing exactly that, showing that she is wary of this stranger she doesn't know.  

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i hope this have an amazing day!

that was alot for five

the answer is : )