Correct Answer & Explanation
Option A
• This sentence states a universal truth or a scientific fact.
• Universal truths, general facts, and habitual actions are expressed in the Present Indefinite (Simple Present) Tense.
• The structure for Present Indefinite Tense is Subject + V1 (base form of the verb), with 's/es' added for a third-person singular subject.
• 'Water' is a third-person singular subject, so 'boils' is the correct form.