$Z * T - S \times U$ Means
$Z$ is the son of $T$, who is the wife of $S$, who is the son of $U$.
i.e. $Z$ is the son of $S$ who is the son of $U$
i.e. $Z$ is the grandson of $U$
$U$ is the daughter of $P$
So, $U$ is the grandmother of $Z$.
So, option (B).