A transgenic mouse animal model is created that expresses both the Cre recombinase gene, under control of a promoter for a gene expressed only in muscle fibers, and an androgen receptor with loxP sites around exon 2. How will expression of the androgen receptor protein be altered in the transgenic mouse

The Cre-lox system triggers recombination of the androgen receptor gene in muscle cells

Explanation:

The Cre-lox system is capable of producing site-specific recombination events in a given DNA region. This technique enables the spatial and temporal control of target gene expression. The Cre-lox system contains a recombinase enzyme (Cre recombinase) that allows the recombination of specific nucleotide sequences (LoxP sequences), being thus used to produce genetic modifications (i.e., insertions, deletions, translocations, inversions, etc.) at target loci where LoxP sequences were inserted.

it would be c. xylem.