Which of the following diseases of poultry is caused by a virus and is characterized by respiratory distress, nervous signs, and greenish diarrhoea?

Newcastle disease (ND) is a highly contagious viral disease of poultry caused by avian paramyxovirus, presenting with respiratory distress, nervous signs such as torticollis, and greenish diarrhoea. Fowl typhoid and cholera are bacterial diseases, while coccidiosis is caused by a protozoan parasite.