﴿ وَيُرِيكُمْ ءَايَٰتِهِۦ فَأَىَّ ءَايَٰتِ ٱللَّهِ تُنكِرُونَ ﴾

“And [thus] He displays His wonders before you: which, then, of God’s wonders can you still deny?”

And He shows you His signs. So which of God’s signs that is the signs that prove His Oneness do you reject? the interrogative here is meant as a rebuke; ayya ‘which of’ is more commonly made masculine than feminine.