4. We will go to the beach if the weather is good. a) first conditional b) second conditional c) zero conditional

The correct answer is a) first conditional. Explanation: The sentence "We will go to the beach if the weather is good" is a conditional sentence where the possibility of going to the beach depends on the weather being good. This is a typical example of a first conditional sentence. The structure of the first conditional is: If + present simple, will + infinitive