If Mary’s daughter is my daughter’s mother, who am I to Mary?
(e) I am Mary
A guy, when he says, “My daughter’s mother”, he is referring to his wife.
A lady, when she says, “My daughter’s mother”, she is referring to herself.
Based on the options given, we can safely assume that it’s not a guy – there is no option for son, father, grandfather, grandson, etc.
So, when a lady says, “My daughter’s mother”, she is actually referring to herself (or ‘me’). And, if we rephrase the sentence, it becomes, “If Mary’s daughter is me, who am I to Mary?”