In the question below, a sentence is provided with one part highlighted in bold. The bold segment may or may not contain a grammatical error. Choose the option that best replaces the highlighted part to make the sentence grammatically correct. If the sentence is already correct as it stands, choose 'No replacement required' as your answer.

Whenever it is raining, waterlogging in streets and roads is the most common problem the city faces.

The correct answer is it rains.

Explanation:
The given sentence describes a general fact, routine event, or habitual occurrence—specifically, what routinely happens in the city whenever a specific weather condition takes place.

In English grammar, time clauses or conditional clauses introduced by conjunctions such as whenever, when, or if that express general truths or habitual occurrences require the Simple Present Tense rather than the Present Continuous Tense.

• Present Continuous Tense ("it is raining"): Used to describe an action happening at the exact moment of speaking.
• Simple Present Tense ("it rains"): Used to describe repeated, habitual actions, or general facts.

Therefore, the present continuous form "it is raining" must be replaced by the simple present form "it rains" to make the sentence grammatically correct.