children in western countries can usually get all kinds of p

选A吧,个人认为第一个填on,然后第二个不用填.第一个之所以填on是因为英语里对于特定的日期,节日和生日前面都要用介词on.
若指在哪一年或哪一月,用介词in；若具体到某一天,需用介词on.例如：
She was born in 1989.
She was born in August.
She was born in August 1989.
She was born on 2nd August, 1989.