给下列对话选择相应的图片⑴—When is Grandpa's birthday?{#blank#}1{#/blank#}
—It's on October 1st. A. 
⑵—When is Grandma's birthday?{#blank#}2{#/blank#}
—It's on April 20th. B. 
⑶—When is mum's birthday?{#blank#}3{#/blank#}
—It's on February 24th. C. 
⑷—When is your birthday?{#blank#}4{#/blank#}
—My birthday is on August 21st. D. 