Read the following passage below and answer the given question <br><br>
Some of the conventional sources of energy have poor efficiency and produce a lot of smoke because of incomplete combustion. A few example are wood, animal dung, agricultural wastes etc; <br><br>
Wood has poor efficiency because only 8% of the wood is utilized as fuel. This results in incomplete combustion. Also, it produces gases like carbon di oxide which is hazardous to our health. <br><br>
Animal dung when mixed with mud and made in the form of cakes,which are then dried and burnt are also used for domestic purpose. As it burns, it produces a lot of smoke and hence results in air pollution. <br><br>
Agricultural wastes like sugarcane are burnt for use in industries. This is more preferable for biogas plants. <br><br><br>
QUESTION : Animal dung and agricultural waste are preferable for
