Durga lives in a village and cooks food on a chulha (earthen stove) using wood and cow dung cakes as fuel. She has been suffering from severe cough for the last three months. This may be due to the -

• A. Carbon monoxide produced by burning fuel which may have been deposited in her respiratory tract
• B. Soot produced by burning the fuels which may have been deposited in her respiratory tract
• C. Smoke produced by burning fuels which may have caused her allergy
• D. Old age and pollution inside and outside her hut