Given that:
$1.$ $A$ is the mother of $B$;
$2.$ $C$ is the son of $A$;
$3.$ $D$ is the brother of $E$;
$4.$ $E$ is the daughter of $B$.
The grandmother of $D$ is:

Introducing Rajesh,Neha said,"His brother's father is the only son of my grandfather." How is Neha related to Rajesh?

If Kamal says,"Ravi's mother is the only daughter of my mother," how is Kamal related to Ravi?

Introducing a man,a woman said,'His wife is the only daughter of my father'. How was that man related to the woman?

$A$ is $B$'s sister. $C$ is $B$'s mother. $D$ is $C$'s father. $E$ is $D$'s mother. Then,how is $A$ related to $D$?

$(i)$ In a family of six persons $A, B, C, D, E$ and $F$,there are two married couples.
$(ii)$ $D$ is the grandmother of $A$ and mother of $B$.
$(iii)$ $C$ is the wife of $B$ and mother of $F$.
$(iv)$ $F$ is the granddaughter of $E$.
What is $C$ to $A$?