which word is wrong or incorrect ?

The salesman recommended that he keeps his receipt for at least a month.
1-recommended-2-keeps-3-receipt-4-at least
my answer is keeps.

Yes, you're right.

Your answer is correct. The word "keeps" is incorrect in the sentence.

To determine which word is incorrect, you can break down the sentence and identify any grammar or tense errors.

In this case, the correct form of the verb should be "keep" instead of "keeps." The sentence is in the subjunctive mood, which is used to express a recommendation or suggestion. In the subjunctive mood, we use the base form of the verb (infinitive) instead of the typical present tense form.

So the correct sentence would be: "The salesman recommended that he keep his receipt for at least a month."

Your answer is correct. The word "keeps" is incorrect in the given sentence. The correct word should be "keep" as it agrees with the verb form used after the word "recommended." The correct sentence would be: "The salesman recommended that he keep his receipt for at least a month."