Bonjour
 CORRECT ANSWER = B
Son amie est en Normandie.
EXPLANATION
Ses amie est en Amérique. ► "ses" is FALSE it's a possessive ad. plural.
 and "amie" is sing. feminine.
Son amie est en Amérique ► correct--> "son" is masc. sing, but as "amie" 
 begins with a vowel, "sa" changes in "son"
Sa amie est en France ► false. see above. "sa" = possessive adj. feminine 
 when the following noun begins with a vowel,it 
 changes in "son"
Sa ami  est à Paris. ► false. "ami" is masculine sing. then the possessive 
 adjective is "son"
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sa + fem. noun. BUT when the following noun begins with a vowel, even if it's a feminine noun, it changes in "son" for the pronunciation --->
son amie, son école, son amoureuse.... all fem. nouns beginning with a vowel...
son + masc. singular noun
ses + plural fem. & masc. ses amies & ses amis
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Hope this helps to understand ☺☺☺
son + masc. noun