Which one of the following pairs of solutions will be expected to be isotonic under the same temperature ?
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 M `Na_(2)SO_(4)`
D. `0.1 M Ca(NO_(3))_(2) and 0.1 M Na_(2)SO_(4)`
