A:祖父→父亲→弟弟
B:祖母→父亲→弟弟
C:外祖父→母亲→弟弟
D:外祖母→母亲→弟弟
下列各项,划线字读音完全正确的一项是( )
Many people have got the habit of buying flowers for their mothers on _______.