下面哪个JSON格式表示(姓名John，年龄30，来自城市New York)是有效的？（ ）
A：{ "name": "John", "age": 30, "city": "New York" }
B：{ "name";"John","age";"thirty","city";"New York" }
C：{ "name": John, "age": 30, "city": "New York" }
D：{ name: "John", age: 30, city: "New York" }
正确答案：A
试卷来源：202412 青少年软件编程等级考试Python六级真题