Henry asked his wife (1)/ what had she prepared (2)/ for dinner that night. (3)/ No error. (4)

Answer

2

Explanation

she had will replace had she because -
in Indirect Speech, Interrogative Sentence, the Sub ject comes before the Verb.
Look at the examples given below:
`{:("She asked, Where does Peter live ? (D.S)"),(" "darr " "darr),(" Subject Verb"),("She asked him where Peter lived. (I.S)"),(" "darr " "darr),(" Subject Verb"):}`