Which one of the following pairs of solution can we expect to be isotonic at the same temperature

Options

A. 0.1 M urea and 0.1 M NaCl
B. 0.1 M urea and 0.2 M `MgCl_(2)`
C. 0.1 M NaCl and 0.1 M `Na_(2)So_(4)`
D. 0.1 M `Ca(NO_(3))_(2)` and 0.1 M `Na_(2)SO_(4)`

Answer

D