Which of the following sign/signs means "NO SMOKING"?用单数还是复数

问题描述:

Which of the following sign/signs means "NO SMOKING"?用单数还是复数

先看句意,
下列标识中哪个表示 禁止吸烟?
从动词 means 推断which 指代的是单数名词, 即 following signs 里面的 一个 sign, following signs 是集合复数,

signs 用复数形式
这些符号中的哪个代表‘请勿吸烟’?

signs 用复数
但谓语动词means用单数,因为主语是which