According to the weather report, the pollution index was________.

A．because the bird had finally understood his threat
B．because the bird managed to escape from the chicken house
C．because the bird had learned to scream back at him
D．because the bird was living peacefully with the chickens

A．is one of the largest oil producers and exporters in the world
B．has done better in fighting against poverty than against unemployment
C．is encountering great dissatisfaction with its oil development in the Niger delta
D．is faced with high unemployment and continued poverty throughout the country