Statement A。然而,Statement B
The conjunction 然而 (rán'ér) means 'however,' 'yet,' or 'nevertheless' and is used to introduce a contrasting statement. It is more formal than 但是 and is common in written Chinese and news reports. For example, 然而他们的身份仍然未知 means 'however, their identities remain unknown.'
他很努力,然而结果并不理想。
Tā hěn nǔlì, rán'ér jiéguǒ bìng bù lǐxiǎng.
He worked very hard; however, the results were not ideal.
天气预报说会晴天,然而下午却下起了雨。
Tiānqì yùbào shuō huì qíngtiān, rán'ér xiàwǔ què xià qǐle yǔ.
The weather forecast said it would be sunny; however, it started raining in the afternoon.
这个方案看起来不错,然而执行起来很困难。
Zhège fāng'àn kàn qǐlái búcuò, rán'ér zhíxíng qǐlái hěn kùnnán.
This plan looks good; however, it is very difficult to implement.