A + B means A is the daughter of B ;
A x B means A is the son of B  and
A - B means A is the wife of B.

If Z x T - S x U + P, what is U to Z.

Answer: B. Grandmother

Z x T - S x 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 or U is the grandmother or grandfather of Z.
Form the choice, (b) is true.