Homeobox genes play a crucial role in controlling the development of body plans in eukaryotic organisms.

Which of the following statements about homeobox genes are correct?

1. They encode a protein domain called the homeodomain, which consists of 60 amino acids.
2. They are only found in vertebrates and are absent in simpler multicellular organisms like fruit flies.
3. They act as regulatory genes by controlling the expression of other genes during development.