In the book "Swiss Family Robinson"...Why do the father and Fritz keep the mysterious note on the albatross a secret from the rest of the family?

A. They do not want the others to know that they are being watched.

B. They do not want the others to know that other people have visited the island.

C. They do not want the others to have false hope that someone else is on the island.

D. They do not want the others to think that they might be rescued soon.