The number 6,743,234,123 is read ____ .

A．Six billion, seven hundred and forty-three million, two hundred and thirty- four thousand, one hundred and twenty-three

B．Six billion and seven hundred and forty-three million and two hundred and thirty four thousand and one hundred twenty-three

C．Six billion and seven hundred and forty-three million and two hundred and thirty four thousand and a hundred and twenty-three

D．Six billions, seven hundreds and forty-three millions , two hundreds and thirty -four thousands a hundred and twenty-three