Which of the following is true regarding the Cre-lox recombination system?
◦ Cre recombinase initiates conjugative transfer of the T-DNA in Agrobacterium tumefaciens.
◦ It can be used to remove selectable markers in transgenic organisms.
◦ Cre recombinase can recognize the P element inverted repeat end sequences.
◦ It is limited to manipulating DNA sequences in vitro.
◦ This site-specific recombination system is derived from Drosophila.