下列生物中，属于竞争关系的是  ( )

A．水稻和杂草

B．猫和老鼠

C．人和猪

D．蚂蚁和蚱蜢

—Do you believe his words?  

—No, what he said was________.

A．less convincing

B．more convincing

C．less convinced

D．more convinced