In a 200 m walk race, Zakia walks at an average speed of 5 km/h. She gives a start of 20 m to Veena and still beats her by 18 seconds. What is the average speed of Veena (in km/h)?

Given, 

Speed of Zakia = 5 km/hr = $$5\times\ \frac{5}{18}=\frac{25}{18}$$ m/s 

Time taken by Zakia to cover 200 m race = $$\frac{200}{\frac{25}{18}}=144\ \sec$$

Time taken by Veena = 144 + 18 = 162 sec

Distance covered by Veena = 200 - 20 = 180 m 

Speed of veena = $$\frac{180}{160}$$ m/s = $$\frac{180}{160}\times\ \frac{18}{5}$$ km/hr

by solving, we get 

Speed of veena = 4 km/hr

Hence, Option C is correct.