B)
1. It's Edward Dunn Malone, John Roxton, and the professor Summerlee who will go on the expedition.
2. Edward is journalist, John likes south america, and the professor want discovert the Amazon.
3. Because he loves South America.
4. They can open the envelope when they will be at Manaos, Edward can write on his envelope.
C.
5. The envelope could contain secret information.
6. There could be dangerous animals, unknown tribes or ruins of ancient civilization.
