All of the above I believe is the correct answer
Sister chromatids have different alleles although carry same genes on same loci. So if it doesn't happen so, like if there are same alleles on sister chromatids then there is a problem in its formation. i.e., male and female alleles haven't contributed equally ( may be an error during their segregation process ). And obviously it doesn't happen in a real cell so we must understand this point. Because normally whenever it happens there's one half from the male and one half from the female. (i.e. maternal and paternal alleles contribute equally).
I hope you get the answer!!!
The correct option is A.
The serosa refers to the outermost layer of loose connective tissues which is often covered by mucus and which contains blood vessels. In the gastrol intestinal tract, the serosa refers to the outermost layer of the wall of the GI tract. One major function of serosa is to reduce friction from muscle movement.
I don’t have your list, but that would be the independent variable, or the IV.
