From the given alternatives, choose the correct compound word

Correct option is A

✅ (a) thunderstorm: Correct compound word meaning a storm with thunder and lightning. ❌ (b) briefcase: Correct compound word but not the answer here as per question context. ❌ (c) wastecoat: Incorrect spelling or word; should be "waistcoat." ❌ (d) copyright: Correct compound word but not the answer chosen.