家庭成员称谓词汇认读 — 英语选择题

晚上，Lily 一家在看家庭相册。妈妈指着一位女士说：She's my mother. 爸爸指着一位男士说：He's my father. 相册里还有一位老爷爷（爸爸的爸爸），用英语应该说是：A. He's my brother. B. He's my grandfather. C. She's my grandmother. D. She's my sister.