What Is the Formula for Calculating Expected Frequencies in the Chi-Square

What is the formula for calculating expected frequencies in the chi-square test for independence?

A) $\left( \frac { \text { Total } _ { \text {row } } } { N } \right) ^ { 2 }$
B) $\frac { \text { Total } _ { \text {rw } } } { N }$
C) $\frac { \text { Total } _ { \text {conwx } } } { N }$
D) $\frac { \mathrm { Total } _ { c a \mathrm { own } } } { \mathrm { N } } \left( \mathrm { Total } _ { \mathrm { ran } } \right)$