Absolute value of z = x + iy is

• A. \(\left| z \right| = \sqrt {\left( {{x^2}{y}} \right)}\)
• B. \(\left| z \right| = \sqrt {\left( {{x^2}/{y^2}} \right)}\)
• C. \(\left| z \right| = \sqrt {\left( {{x^2} - {y^2}} \right)}\)
• D. \(\left| z \right| = \sqrt {\left( {{x^2}+{y^2}} \right)}\)