K की ओर इशारा करते हुए M कहती है कि, वह उसके दादा के एकमात्र पुत्र की पुत्री थी| M, K से कैसे सम्बन्धित है?

The only son of M's grandfather is M's father. M says K is the daughter of that man, so K is M's father's daughter, i.e. M's sister (M is female, being referred to as 'she'). So M is K's sister.