In no particular order, here are three correct answers to the quiz:
1. Offering salat (Islamic prayer)
2. Touching the Quran in book form
3. Making tawaf i.e. walking in a circuit around the Kaaba, the holiest site in Islam
(If you said, “reading the Quran,” I might give you partial credit. One can recite the Quran from memory without wudu. One can also read Arabic excerpts from the Quran in other books without wudu. In today’s modern age, one can even read the Quran on a computer screen without wudu. But to read the Quran in its traditional book form or mushaf, one needs wudu.)
What about conversion (or reversion)?
My understanding is that conversion only requires the public recitation of the shahada (testimony of belief), but Allah knows best. Some recommend making wudu either before or after. Some people recommend ghusl (ritual bath, a more thorough washing than wudu). But I have not found any authority who says that conversion requires wudu, and again Allah knows best.