The price of an article is reduced by 25%. In order to retain the original price, the present price has to be increased by :

Answer: Option C

Let the original price = Rs. 100
New price = Rs. 75
Increase on 75 = 25
Increase on 100 :
$$\begin{array}{rl}& =\left(\frac{25}{75}\times 100\right)\%\\ & =\frac{100}{3}\%\\ & =33\frac{1}{3}\%\end{array}$$