Topic: Fill in the Blank,

Best Answer Explained in Below-:

In the sentence "My wife ___ the dinner, because I had already cooked it," we need to choose an option that accurately conveys the idea that it was unnecessary for the wife to cook because the speaker had already done so.

Option A, "needn't have cooked," suggests that she cooked dinner but that it was not needed; however, the structure implies she did cook, which does not fit the context set by "because I had already cooked it."

Option C, "wouldn't cook," implies a decision or unwillingness to cook, which does not address whether she needed to cook dinner in the first place.

Option D, "may not have cooked," introduces uncertainty about whether she cooked at all, which again does not align with the idea of explaining why it wasn’t necessary.

Option B, "didn't have to cook," is the most fitting choice. It clearly indicates that cooking dinner was unnecessary for her because the speaker had already prepared it. This phrase emphasizes a lack of obligation or requirement to cook, accurately reflecting the context provided. Thus, option B effectively completes the sentence and conveys the intended meaning.