Correct the following equation by interchanging the two signs and two numbers 

$7\times 6+5-4=33$

$\begin{array}{l}7\times 6+5-4=33\\ 7-6+4\times 5=33\\ 7-6+20=33\end{array}$

$21\ne 33$ (wrong)

Option (b)

$\begin{array}{l}7\times 6+5-4=33\\ 7+6\times 4-5=33\\ 7+24-5=33\\ 26\ne 33\text{ (wrong) }\end{array}$

Option (c)

$\begin{array}{l}7\times 6+5-4=33\\ 7\times 5-6+4=33\\ 35-6+4=33\\ 33=33\text{ (right) }\end{array}$

Option (d)

$\begin{array}{l}7\times 6+5-4=33\\ 7-5+6\times 4=33\\ 7-5+24=33\\ 26\ne 33\text{ (wrong) }\end{array}$