Choose the grammatically correct sentence:

The correct answer is Option (1) → If Aarav knew how to swim, he would join his friends at the pool every Sunday.

If-sentence about an imagined present:

• Aarav cannot swim now. To imagine a different present, we use If + simple past, ... would + verb.
• So the if-part takes knew, and the second part takes would join.

Why the Other Options are Incorrect?

Option 2: If Aarav will know how to swim, he would join his friends at the pool every Sunday. — Incorrect. “Will” is not used right after “if”.

Option 3: If Aarav knows how to swim, he would join his friends at the pool every Sunday. — Incorrect. “Knows” is the simple present. It does not go with “would join” in the second part.

Option 4: If Aarav would know how to swim, he would join his friends at the pool every Sunday. — Incorrect. “Would” belongs only in the second part, never right after “if”.