Solve For $z$ In Terms of the Other Variables $z=\sqrt{x^{2}+y^{2}}$ B) $x^{2}+y^{2}$ C) $z=\sqrt{y^{2}-x^{2}}$

Solve for $z$ in terms of the other variables.

A) $z=\sqrt{x^{2}+y^{2}}$
B) $x^{2}+y^{2}$
C) $z=\sqrt{y^{2}-x^{2}}$
D) $z=\sqrt{x^{2}-y^{2}}$